Thank you to everyone who reports issues
Every question in our bank has been written and reviewed carefully, but with thousands of problems spanning a dozen engineering disciplines, errors happen. When a user takes the time to work through a problem, verify the math, and send us a detailed report — that’s a genuine contribution to the quality of the question bank for every future test-taker. We read every report, verify every claim independently, and push fixes as quickly as possible. This page is our public record of confirmed corrections.
How to Report an Issue
If you believe a question has a wrong answer, a calculation error, or misleading wording, please contact us with:
- The Question ID (shown in the app when you review a question)
- A brief description of what you believe is wrong
- Your working, if you have it — even a rough sketch helps
We aim to respond and verify within 48 hours. If your report checks out, we will update the question bank and credit the correction here.
Confirmed Corrections
| Date | Exam | Topic | Description | Status |
|---|---|---|---|---|
| 2026-10-10 | PE Civil Structural | Rounding correction, Q21044 | The sawn-lumber column factor is 0.5578965. Option B is corrected from 0.55 to 0.56; the solution must round consistently. | Prepared for next app release |
| 2026-10-10 | PE Civil Structural | Code-model correction, Q21063 | Use the ACI 318-14 Section 27.4.2.2 total load-test combinations. With the stated absent roof loads, max(242, 182, 104) = 242 psf including existing dead load. Option C changes from 240 to 242 psf; the old formula is superseded. | Prepared for next app release |
| 2026-10-10 | PE Civil Structural | Question replacement, Q21142 | The old blanket continuous-inspection claim for CJP welds is withdrawn. The replacement asks which standard governs structural-steel quality assurance under IBC 2018 Section 1705.2.1: A, AISC 360. Do not apply the new options to the old stem. | Prepared for next app release |
| 2026-10-10 | PE Civil Structural | Duplicate replacement, Q21262 | The duplicate glulam calculation is replaced by a wood drying question. Its answer B states that tangential shrinkage generally exceeds radial shrinkage while longitudinal shrinkage is much smaller. The old glulam stem still computes 1,728 psi; it must not be paired with the replacement options. | Prepared for next app release |
| 2026-10-10 | PE Civil Transportation | Crossing-gap correction, Q20134 | The single-unit-truck crossing case uses an 8.5-second two-lane base and 0.7 second per extra lane. For six lanes, 8.5 + 4(0.7) = 11.3 seconds, option C. The old 9.5-second result used incorrect vehicle adjustments; stem and options are corrected together. | Prepared for next app release |
| 2026-10-10 | PE Civil Transportation | Question replacement, Q20024 | The crown-drop calculation is replaced by a barrier-clearance concept question. Answer A identifies barrier deflection and vehicle intrusion behind its original face as a potential collision with the pier. The former calculation remains 0.24 ft; do not pair its stem with the new options. | Prepared for next app release |
| 2026-10-09 | PE Civil Structural | Answer correction, Q21393 | Wind is uplift, not a positive gravity contribution. With favorable wind absent, 1.2D + 1.6S = 68.8 kip-ft governs. The answer changes from C (75.8 kip-ft) to A (68.8 kip-ft). | Prepared for next app release |
| 2026-10-09 | PE Civil Structural | Answer correction, Q21293 | All listed suspended equipment is included in gross load. The total is 42,000 lb against 60,000 lb gross chart capacity, giving 70.0%. Option D previously read 68%. | Prepared for next app release |
| 2026-10-09 | PE Civil Structural | Question replacement, Q21061 | The ambiguous numerical sweep-tolerance question is replaced with a distinction among sweep, camber, dimensional variation and twist. C identifies lateral centerline deviation in plan. The old 1/8-in-per-10-ft choice does not apply to the replacement. | Prepared for next app release |
| 2026-10-09 | PE Civil Structural | Grading clarification, Q21278 | The stem now explicitly assumes a compact section with yielding governing and specifies rounding an exact half upward. Design strength is 412.5 kip-ft, entered as 413 kip-ft. The app tolerance changes from 5 to 0.01 kip-ft so it no longer accepts adjacent whole-number answers. Compactness cannot be inferred from A992 steel grade alone. | Prepared for next app release |
| 2026-10-09 | PE Civil Structural | Question and answer correction, Q21400 | The revised wall locations and stiffnesses define a consistent center of rigidity. Direct W2 shear is 46.1538 kips; the governing torsional addition is 25.6684 kips. D is 71.8 kips, replacing 74.9 kips. Use the revised geometry and solution together. | Prepared for next app release |
| 2026-10-09 | PE Civil Structural | Question and answer correction, Q21410 | The U-shaped line weld is defined with its horizontal weld at the top and an out-of-plane bending moment. The line inertia is 504 in cubed and the extreme distance is 7.50 in. Combined line force is 6.05 kip/in against 11.1384 kip/in strength: B, adequate. The previous B value was 5.0 kip/in. | Prepared for next app release |
| 2026-10-09 | PE Civil Structural | Answer correction, Q21409 | Snow includes the 5-psf rain-on-snow surcharge, so S = 45 psf. Roof live load and snow are alternatives in the supplied LRFD combination. The governing load is 1.2(22) + 1.6(45) = 98.4 psf. C previously read 104.4 psf. | Prepared for next app release |
| 2026-10-09 | PE Civil Structural | Answer correction, Q21146 | For the stated ordinary-length bolting assemblies, RCSC pre-installation verification requires 1.05 times the minimum installation pretension, rounded to the nearest kip. D is corrected; the previous choice stated only the full installation minimum. | Prepared for next app release |
| 2026-10-09 | PE Civil Transportation | Answer wording correction, Q20610 | A remains correct after repair: underpass sight distance may require a longer sag curve, but the drainage limit is an upper bound on K and length for fixed grade difference. Shortening improves that grade check. The old wording incorrectly said drainage could require a longer curve. | Prepared for next app release |
| 2026-10-09 | PE Civil Transportation | Question replacement, Q20106 | The unsupported universal 4-in curb-height recall is replaced by a conceptual comparison. B explains that a low sloping curb reduces abrupt wheel interaction and vehicle destabilization relative to a tall vertical face; it does not guarantee containment or waive roadside-safety checks. | Prepared for next app release |
| 2026-10-09 | PE Civil Transportation | Question and answer correction, Q20154 | The replacement supplies the complete AASHTO 1993 rigid-pavement equation and missing load-transfer coefficient J = 3.2 and terminal serviceability 2.5. The continuous solution is 8.98459 in, most nearly B (9.0 in). The old supplied nomograph choice was 9.5 in; use the replacement equation and solution together. | Prepared for next app release |
| 2026-10-09 | PE Civil WRE | Answer correction, Q40225 | The Hazen-Williams excerpt paired the SI coefficient 10.67 with flow in cfs and diameter in feet. For those units the coefficient is 4.73. The friction head loss is 24.6 ft, so the answer is 25 ft; it previously read 56 ft. | Released in the app |
| 2026-10-09 | PE Civil WRE | Answer correction, Q40037 | Runoff depth is 3.99 in over 500 acres, 166 ac-ft. Option D read 175 ac-ft and now reads 166 ac-ft; D remains the key. | Released in the app |
| 2026-10-09 | PE Civil WRE | Answer correction, Q40034 | The supplied NRCS lag equation gives 1.09 hr. Option B read 1.2 hr and now reads 1.09 hr; B remains the key. | Released in the app |
| 2026-10-09 | PE Civil WRE | Answer correction, Q40092 | The stated removal did not match the NRC equation for the supplied loading. The equation is now supplied with consistent units, removal is 74.4% and the effluent BOD is 33.3 mg/L. Option B read 38 mg/L; B remains the key. | Released in the app |
| 2026-10-09 | PE Civil WRE | Question revision, Q40153 | The stem now supplies a measured liquid flux for the geomembrane in place of a vapor transmission rate, and the clay-liner gradient includes the elevation head, (h + L)/L = 3.5. The ratio is 30,240; option B read "approximately 20,000 times less". B remains the key. | Released in the app |
| 2026-10-09 | PE Civil WRE | Answer correction, Q40084 | The stem now states the exit-loss coefficient (1.0), and a roughness value that conflicted with the supplied friction loss was removed. Headwater is 6.27 ft. Option D read 6.5 ft; D remains the key. | Released in the app |
| 2026-10-09 | PE Civil WRE | Answer correction, Q40139 | The critical deficit is 5.39 mg/L. Option D read 5.6 mg/L and now reads 5.39 mg/L; D remains the key. | Released in the app |
| 2026-10-09 | PE Civil WRE | Answer correction, Q40165 | The Cooper-Jacob radius of influence is 5,817 ft. Option C read 5,600 ft; C remains the key. Drawdown data that conflicted with the aquifer properties was removed from the stem. | Released in the app |
| 2026-10-09 | PE Civil WRE | Answer correction, Q40233 | The supplied equation gives 4.41 ft. Option B read 4.2 ft; B remains the key. | Released in the app |
| 2026-10-09 | PE Civil WRE | Answer correction, Q40082 | The depth in the contraction is 3.31 ft. Option C read 3.2 ft; C remains the key. The other options no longer let the answer be chosen without computing it. | Released in the app |
| 2026-10-09 | PE Civil WRE | Answer correction, Q40135 | The Hardy Cross correction is +12.8 gpm. Option C read +12 gpm; C remains the key. | Released in the app |
| 2026-10-09 | PE Civil WRE | Answer correction, Q40178 | The itemized total is $313,950. Option C read $312,000; C remains the key. | Released in the app |
| 2026-09-30 | PE Civil Structural | Answer correction, Q21311 | Recomputed with the ASCE 7-16 interior-column live-load element factor KLL = 4: L = 50(0.25 + 15/√2400) = 27.8 psf, above the 25 psf minimum for one supported floor, so 28 psf. The key (B) previously read 34 psf. | Released in the app |
| 2026-09-30 | PE Civil Structural | Answer correction, Q21320 | Recomputed with KLL = 4 and the cumulative 1,500 ft² tributary area of five floors: L = 80(0.25 + 15/√6000) = 35.5 psf, above the 32 psf (40%) minimum for multiple floors. The key (B) previously read 42 psf. | Released in the app |
| 2026-09-30 | PE Civil Structural | Answer correction, Q21050 | Recomputed under AISC 360-16 J3.8, the exam’s current steel standard: φRn = 0.30 × 1.13 × 1.0 × 28 kips × 4 bolts = 38.0 kips. The key (B) previously read 44.3 kips. | Released in the app |
| 2026-09-30 | PE Civil Structural | Answer correction, Q21102 | Recomputed under AISC 360-16 G2.1 without tension-field action: h/tw = 128, Cv1 = 0.478, Vn = 0.6(50)(50 × 0.375)(0.478) = 269 kips. The key (A) previously read 144 kips; the figure now labels the 50 in overall depth separately from the 48 in clear web depth. | Released in the app |
| 2026-09-30 | PE Civil Structural | Answer correction, Q21325 | The primary-girder flexibility coefficient uses the 40 ft secondary span, not the 10 ft spacing: Cp = 2.29, Cs = 0.82, so Cp + 0.9Cs = 3.02 (AISC 360-16 Appendix 2.1, limit 0.25). The key (C) previously read 1.31. | Released in the app |
| 2026-10-05 | PE Civil Structural | Answer correction, Q21111 | The compression steel does not yield, and the concrete it displaces is now subtracted: strain compatibility gives 59.5a2 − 260.7a − 208.8 = 0, so a = 5.07 in. with f′s = 52.7 ksi. The key (D) previously read 4.84 in. The figure now labels the overall depth h instead of repeating d = 22 in. | Released in the app |
| 2026-10-05 | PE Civil Structural | Answer correction, Q21056 | Anchor steel strength in tension uses the effective threaded area, not the gross shank area (ACI 318-14): φNsa = 0.75 × 4 × 0.334 in² × 75 ksi = 75.2 kips. The key (C) previously read 99.4 kips, which is the gross-area result. | Released in the app |
| 2026-10-05 | PE Civil Structural | Answer correction, Q21173 | For exposure classes S1 and F2 under ACI 318-14, F2 governs at w/cm 0.45 and 4,500 psi, Type II cement is permitted, and the target air content for 3/4-in. aggregate is 6.0%. The correct selections are now A, B, C and D; the key previously read A, B and D with different option wording. The stem now states normalweight, cast-in-place concrete and the aggregate size. | Released in the app |
| 2026-10-05 | PE Civil Structural | Answer correction, Q21276 | Freezing with frequent water and deicing chemicals is exposure class F3 with C2, not F2: maximum w/cm is 0.40 and minimum f′c is 5,000 psi (ACI 318-14). Options A and B previously read 0.45 and 4,500 psi. The selections remain A, B, C and E; C now states the 6.0% target air content and E the cover for #3 through #11 bars. | Released in the app |
| 2026-10-05 | PE Civil Structural | Answer correction, Q21324 | The ASCE 7-16 vehicle-barrier load of 6,000 lb acts at the height between 18 and 27 in. that gives the greatest effect. For a single fixed-base post carrying the whole force, M = 6 kips × 2.25 ft = 13.5 kip-ft. The key (A) previously read 9 kip-ft. This question also appears in the PE Civil Structural book. | Released in the app |
| 2026-10-05 | PE Civil Structural | Question revision, Q21181 | The bolted-connection ordering question asked for a fixed order among limit-state checks that can be done in any order. The steps are rewritten so each depends on the one before: bolt strength, bolt count, trial layout, the grouped strength checks, then acceptance. The correct order changed with the new steps. | Released in the app |
| 2026-10-05 | PE Civil Structural | Question revision, Q21280 | The spread-footing ordering question placed loads before the soil investigation, which are independent. Loads and allowable net soil pressure are now given, and the steps follow one design pass: plan dimensions, factored soil pressure and demands, shear depth, flexural steel, then anchorage and detailing. The correct order changed with the new steps. | Released in the app |
| 2026-09-29 | FE Electrical and Computer | Answer correction, Q217 | The built-in voltage of the silicon p-n junction is (kT/q) ln(NAND/ni2) = 0.02585 × ln(4.44 × 1011) = 0.693 V. Option B read 0.72 V and now reads 0.69 V; B remains the key. The other options now match named errors: base-10 log (0.30 V), dropping the square on ni (1.30 V) and ni = 1.5 × 109 (0.81 V). | Released in the app |
| 2026-09-27 | PE Computer Engineering | Question revision, Q50200 | Option B (1.25 MB/s) was the correct 10 Mbps throughput written in bytes per second, so two options were right. Option B now reads 5 Mbps, the result of splitting one clock between the two directions. The key (C, 10 Mbps) is unchanged. | Released in the app |
| 2026-09-27 | PE Computer Engineering | Solution text corrections, Q50080, Q50318, Q50448, Q50456 | Keys unchanged. The worked solutions named the wrong option letters (Q50080) and the wrong product term (Q50318), called A = 11 correct in hexadecimal (Q50448), and included a false bit-comparison sentence (Q50456). All four were corrected, along with the step order in 59 PE Computer Engineering solutions. | Released in the app |
| 2026-09-27 | PE Computer Engineering | Explanation correction, Q50472 | The key (C, 9 page faults) was correct, but the explanation said 7 faults is the FIFO result with 4 frames. FIFO with 4 frames gives 10 faults (Bélády’s anomaly), and 7 is the optimal algorithm’s count with 3 frames. The calculator walkthrough also named the wrong evicted pages; FIFO evicts 0, then 1, 2 and 3, then 0 and 1. Both were corrected. | Released in the app |
| 2026-09-24 | FE Mechanical | Question revision, Q8517 | Question wording revised to require process judgment rather than repeat a supplied answer note. A/B/D remain correct: die casting is a candidate, high volume can justify its tooling cost, and aluminum is nonferrous. | Released in the app; any affected print refresh pending |
| 2026-09-24 | FE Mechanical | Question revision, Q8541 | Question wording revised to interpret heat-treatment behavior rather than copy a supplied note. A/B/D remain correct: tempering reduces brittleness, lower hardness is consistent with tempering, and the as-quenched condition has relatively low toughness. | Released in the app; any affected print refresh pending |
| 2026-09-24 | FE Mechanical | Question revision, Q8593 | Option D now states the physical meaning of Froude similarity instead of referring to an answer-bearing table. A/B/D remain correct; no numerical answer changes. | Released in the app; any affected print refresh pending |
| 2026-09-24 | PE Civil Transportation | Question revision, Q20388 | The supplied clear-zone range used the wrong foreslope column. For the stated 45 mph, ADT 3,000 and 1V:4H fill foreslope, the cited range is 20 to 26 ft. With the stated lower-end project decision, option B is 20 ft, not 16 ft. The revised excerpt includes adjacent conditions; site judgment remains necessary. | Released in the app; any affected print refresh pending |
| 2026-09-24 | PE Civil Transportation | Question revision, Q20536 | Option A now calls for evaluating drainage/undercut alternatives and testing any proposed chemical stabilization. The original 48 percent passing No. 200 is not USCS fine-grained soil, and PI 9 alone does not establish lime-treatment suitability. The answer remains A. | Released in the app; any affected print refresh pending |
| 2026-09-24 | PE Civil Structural | Question revision, Q21476 | The revised question asks about detailing defects rather than restating the note. A/B/C remain correct: grout is needed for the designed composite action, an 8-ft bond-beam gap exceeds the specified 4 ft, and one additional jamb bar is fewer than the specified two. These are requirements of the stated detail, not universal jamb-bar counts. | Released in the app; any affected print refresh pending |
| 2026-09-24 | PE Civil WRE | Question revision, Q40408 | Option E now asks for the consequence of a delay: under the stated fixed-logic CPM assumptions, a 2-day delay to zero-float Activity E delays completion by 2 days. A/B/C/E remain correct. | Released in the app; any affected print refresh pending |
| 2026-09-24 | PE Civil WRE | Question revision, Q40419 | The protection criterion includes trenches exactly 5 ft deep; the previous deeper-than-5 wording was incomplete. Option D now applies competent-person inspection to employee reentry after rain. A/C/D remain correct for the stated 7-ft Type C trench. | Released in the app; any affected print refresh pending |
| 2026-09-24 | PE Civil WRE | Question revision, Q40424 | The inspection schedule is now expressly a project-specific permit condition, not a universal federal requirement. A/C/E remain correct for the revised dated scenario: September 16 at 9 a.m. storm deadline, repair the fence bypass, and September 18 routine inspection. | Released in the app; any affected print refresh pending |
| 2026-09-24 | PE Electrical Power | Question revision, Q30465 | The DGA question now requires diagnosis from main-tank trends. A/C/E remain correct. Revised C requires prompt validation while separately considering immediate protective action; repeat sampling must not be read as permission to delay necessary protection. | Released in the app; any affected print refresh pending |
| 2026-09-24 | PE Electrical Power | Question revision, Q30474 | Option D now relates near-zero operate current to balanced through-load rather than a supplied answer note. A/C/D remain correct for the stated test. | Released in the app; any affected print refresh pending |
| 2026-09-24 | PE Electrical Power | Question revision, Q30485 | Option C has been corrected: select voltage-rated shock protection and arc-flash protection for their respective risk assessments and task. An arc-flash label alone does not determine all shock protection. A/B/C remain correct; the revised question is a preauthorization review, not permission to work energized. | Released in the app; any affected print refresh pending |
| 2026-09-24 | PE Electrical Power | Question revision, Q30490 | The question now asks for functional corrective actions rather than copying checklist findings. A/B/C restore the gate bond, designed worker surface layer and damaged grounding connection. Repainting does not restore electrical continuity. | Released in the app; any affected print refresh pending |
| 2026-09-24 | PE Electrical Power | Question revision, Q30515 | The question now asks for corrective actions: A/B/C/E restore strike termination, down-conductor continuity, surge protection and the specified bond. A warning placard cannot repair a failed protective device. | Released in the app; any affected print refresh pending |
| 2026-09-24 | PE Computer Engineering | Question revision, Q50664 | Option D now describes an actual outbound HTTPS packet using TCP destination port 443. A/D remain permitted by the supplied ordered rules; the interpretation is unchanged. | Released in the app; any affected print refresh pending |
| 2026-09-24 | PE Computer Engineering | Question revision, Q50691 | The revised evidence must identify release R42 and apply the acceptance criteria. A/C/D remain correct; the coverage report requires computing 960 of 1,000 requirements as 96 percent. | Released in the app; any affected print refresh pending |
| 2026-09-24 | PE Computer Engineering | Question revision, Q50728 | Options now require applying the memory map to explicit addresses. A/C remain allowed: user instruction fetch at 0x08000120 and privileged data write at 0x40000024. | Released in the app; any affected print refresh pending |
| 2026-09-24 | PE Civil Transportation | Median-barrier screening, Q20028 | Option D has been corrected. A 60-ft median and ADT of 15,000 fall in the optional-installation range of the stated high-speed, fully controlled-access screening guidance. That screen alone does not establish adequate clear zone or prove that a barrier is unnecessary; crash history and other site risks still require evaluation. | Corrected in source; print refresh pending |
| 2026-09-24 | PE Civil Transportation | Flagger sight distance, Q20148 | The question now supplies the missing table and asks for additional sight distance: 360 − 310 = 50 ft, Option A. The previous question asked for the total 360 ft; that value remains the criterion, not the answer to the revised request. | Revised in source; release pending |
| 2026-09-24 | PE Civil Structural | Concrete acceptance, Q21062 | The question now supplies both acceptance criteria and asks for the next acceptable strength test. With specified strength 4,500 psi and preceding results 4,400 and 4,800 psi, the rolling average governs at 4,300 psi, Option B. The former 500 psi answer described an individual-test shortfall, a different request. | Revised in source; print refresh pending |
| 2026-09-24 | PE Electrical Power | Emergency lighting, Q30017 | The question now includes the lighting criteria and asks which test condition needs correction. Only the end-of-test minimum fails: 0.05 fc is below 0.06 fc. Option A calls for improving that minimum while preserving the other criteria. The former question asked for the initial average criterion of 1.0 fc. | Revised in source; release pending |
| 2026-09-24 | FE Electrical and Computer | Bridge rectifier, app Q68 | Option B should read 9.44 V, not 9.91 V. For a resistive load without filtering, integrate the rectified sine minus the two constant diode drops over its conducting interval. Subtracting the drops from the peak before applying the ideal full-wave averaging factor gives the wrong average. | Corrected in source; release pending |
| 2026-09-24 | PE Computer Engineering | Hamming (7,4), app Q50464 | Option B should read Position 1. For received word 1011001 with the stated left-to-right positions, S1 = 1, S2 = 0 and S4 = 0, so S4S2S1 is 001. Flipping bit 1 gives 0011001 and zero syndrome. The former Position 3 answer was incorrect. | Corrected in source; release pending |
| Aug 24, 2026 | FE Civil | Available Net Positive Suction Head (Q5161) | The selected option’s value was corrected from 20.7 ft to 21.9 ft. Applying Bernoulli from the open reservoir to the pump suction and then using the NPSH definition shows that the stated 1.2-ft suction velocity head cancels; subtracting it again double-counted that term. The corrected calculation is 34 − 8 − 3.5 − 0.6 = 21.9 ft. The answer letter remains B. | Fixed |
| Aug 16, 2026 | PE Civil Structural | Plate-Girder Transverse Stiffener Requirement (Q21028) | The prior key stated that transverse stiffeners were not required. With a 48 in × 3/8 in web, h/tw = 48/0.375 = 128, while the supplied AISC geometric check exempts stiffeners only when h/tw ≤ 2.46√(E/Fy) = 2.46√(29,000/50) = 59.2. Because 128 far exceeds 59.2, the web-slenderness check does require stiffeners. The keyed answer was corrected from "stiffeners not required" to "stiffeners required". | Fixed |
| Aug 16, 2026 | PE Civil Structural | Direct-Analysis Notional Lateral Load (Q21099) | The prior key used 5.0 kips, which corresponds to a 0.0025 coefficient. The supplied AISC 360 direct-analysis relation is Ni = 0.002αYi with α = 1.0 for LRFD, so for a factored story load of Yi = 2,000 kips the notional lateral load is 0.002(1.0)(2,000) = 4.0 kips. The keyed answer was corrected from 5.0 kips to 4.0 kips. | Fixed |
| Aug 16, 2026 | PE Civil Structural | Column Critical Stress (Q21199) | The selected option’s value was corrected from 41.2 ksi to 40.9 ksi after the flexural-buckling stress was re-derived from the supplied relation. The answer letter did not change, but the printed value did, so a book or PDF showing 41.2 ksi is out of date. | Fixed |
| Aug 16, 2026 | PE Civil Structural | Bolt Shear Strength (Q21396) | The selected option’s value was corrected from 95.4 kips to 107.4 kips after the nominal shear stress was realigned with the supplied AISC Table J3.2 case. The answer letter did not change, but the printed value did, so a book or PDF showing 95.4 kips is out of date. | Fixed |
| Aug 16, 2026 | PE Civil Transportation | Work-Zone Merging Taper Length (Q20067) | The prior key used 500 ft, which follows from neither branch of the supplied MUTCD Table 6C-4 rule. At a posted 50 mph the L = WS branch applies (speeds of 45 mph or more), so with a 12-ft lateral offset the minimum merging taper is 12(50) = 600 ft. The keyed answer was corrected from 500 ft to 600 ft, and the distractor rationales were rebuilt to state the offset width each wrong option would imply. | Fixed |
| Aug 15, 2026 | PE Civil WRE | Ductile Iron Pressure Class (Q40062) — supersedes the May 16, 2026 entry below | The earlier correction (to Pressure Class 200) added the 50-psi calculated surge on top of the 150-psi working pressure. ANSI/AWWA C150 pressure classes already include a standard surge allowance of at least 100 psi, and the actual surge is used only when it exceeds that allowance. Because 50 psi is below the included allowance, selection is made on the 150-psi working pressure, so the minimum listed class is Pressure Class 150. The stem now states the C150 rule explicitly and the keyed answer was corrected from Pressure Class 200 to Pressure Class 150. The May 16, 2026 entry below is superseded and its stated answer is no longer correct. | Fixed |
| Aug 14, 2026 | PE Civil Structural | Live-Load Reduction, Four Supported Floors (Q21013) | The prior solution used one floor's 500 ft² tributary area even though the member supports four floors. The corrected stem makes the cumulative area explicit: AT = 4(500) = 2,000 ft². With KLL = 4 and the supplied reduction relation, 50[0.25 + 15/√(4×2,000)] = 20.885 psf; the supplied 0.40L0 minimum is 20.0 psf and does not govern. The keyed answer was corrected from 29.2 psf to 20.9 psf, and the option set and solution were rebuilt. | Fixed |
| Aug 13, 2026 | PE Civil WRE | Compound Channel — Divided-Channel Discharge (Q40279) | The solution stated the divided-channel rule correctly — exclude the imaginary vertical interfaces from each subsection's wetted perimeter — and then did not apply it, using a 32-ft main-channel perimeter that counts those interfaces as solid bank. The floodplain bed sits 4 ft above the main-channel bed, so the main channel's solid boundary is 20 + 2(4) = 28 ft. That gives R = 4.286 ft, Qmain = 421 cfs, and a total of 421 + 2(58.4) = 538 cfs. The answer key moved from 502 cfs to 538 cfs, option D was corrected from 549 cfs to 538 cfs so the key is exact, and the worked solution and calculator steps were rebuilt. This is the same defect class as the Q40081 compound-channel correction below. | Fixed |
| Aug 12, 2026 | FE Civil, FE Mechanical, FE Other Disciplines | Mohr's Circle Figures (20 problems) | The Mohr's circle figure printed its computed results — the principal stresses and the maximum shear stress — as labels on the drawing itself. For 20 of the 21 problems that use this figure, that placed the keyed answer on the diagram. Every one of those problems already states the applied stresses in the text, so the labels were never needed to work the problem. The figure now shows the circle, its centre and the plotted stress points without the derived values. No answer key, option set, or written solution changed. Found during an internal diagram audit. The printed and Kindle editions are covered separately below. | Fixed |
| Aug 12, 2026 | PE Civil Structural | ACI Development Length, #7 Bar (Q21244) | Follow-up to the Aug 7 correction below. The answer options were updated then, but the step-by-step solution still divided by 25 and finished at 56.4 in. — a value that matched none of the options. The written solution now uses the No. 7 and larger denominator of 20 throughout: base length 41.5 in., and with the capped top-bar/epoxy factor of 1.7, 70.6 in., most nearly 71 in. The keyed answer was already correct and did not change. | Fixed |
| Aug 7, 2026 | PE Civil Structural | ACI Development Length, #7 Bars (Q21200, Q21244) | Both problems used the ACI 318-19 Table 25.4.2.3 denominator for No. 6 and smaller bars (25) on a #7 bar, which belongs to the No. 7 and larger row (denominator 20). Q21200 now reads 41.5 in., most nearly 42 in. Q21244's base length is 41.5 in. and, with the capped top-bar/epoxy factor of 1.7, 70.6 in., most nearly 71 in. The answer options and full solutions were corrected in both. A separate item, Q21320, stated a live-load reduction minimum of 0.50L0; a member supporting five floors uses 0.40L0, so that explanation was corrected. Q21320's answer did not change. | Fixed |
| Aug 7, 2026 | FE Electrical & Computer | CRC Remainder (Q3438) | The answer key and written explanation were correct, but the calculator steps and the frame diagram both displayed the remainder as 011 instead of 001. Dividing 1101000 by 1011 in modulo-2 arithmetic leaves 001, giving codeword 1101001. Both displays were corrected; the key and solution arithmetic did not change. | Fixed |
| Aug 7, 2026 | PE Civil Structural | ASCE 7 Wind and Snow Relations (Q21014, Q21015) | Both problems required an ASCE 7 relation that was not printed in the question. The velocity-pressure equation and the flat-roof snow equation are now supplied in the stem, so each item can be solved from the information given. Answers and solutions are unchanged. | Fixed |
| Aug 7, 2026 | PE Computer Engineering | IEEE Reference Values (Q50003, Q50194, Q50344) | Three problems depended on an IEEE value that was not printed in the question: the IEEE 754 exponent bias, the 4-byte IEEE 802.1Q VLAN tag size, and the IEEE 802.1D convergence relation. Each is now supplied in the stem. Answers and solutions are unchanged. | Fixed |
| May 16, 2026 | PE Civil WRE | Open Channel Normal Depth (Q40310) | The trapezoidal-channel Manning calculation was understated. At 2.0 ft depth, the stated channel carries about 39.8 cfs, not 50 cfs; solving gives approximately 2.25 ft, so the closest listed answer was corrected to 2.2 ft. Found during a PE WRE content review. | Fixed |
| May 16, 2026 | PE Civil WRE | Geomembrane Leakage Comparison (Q40153) | The compacted clay liner unit conversion and geomembrane equivalent-depth conversion were corrected. The comparison is now approximately 20,000 times less leakage for the intact geomembrane under the stated assumptions. Found during a PE WRE content review. | Fixed |
| May 16, 2026 | PE Civil WRE | Advection-Dispersion Concentration (Q40146) | The explanation previously computed about 482 mg/L from the stated 1-D advection-dispersion model but then selected 310 mg/L using an unsupported attenuation adjustment. The option and solution were corrected to the nearest stated-model result, 480 mg/L. Found during a PE WRE content review. | Fixed |
| May 16, 2026 | PE Civil WRE | Secondary Clarifier Solids Loading (Q40099) | The SLR-controlled clarifier diameter should round up from about 64.5 ft to 65 ft per clarifier, not 64 ft. The answer option, explanation, and calculator steps were corrected. Found during a PE WRE content review. | Fixed |
| May 16, 2026 | PE Civil WRE | Ductile Iron Pressure Class (Q40062) | The stem asked for the minimum pressure class for a stated 200 psi total pressure. Pressure Class 200 is the minimum listed class that satisfies that requirement; the answer key was corrected from Pressure Class 250 to Pressure Class 200. Found during a PE WRE content review. | Fixed |
| May 16, 2026 | PE Civil WRE | Series Pipe Hazen-Williams Flow (Q40056) | The stated Hazen-Williams series-pipe equation and 50 ft available head solve to approximately 1,060 gpm. The prior listed answer of 290 gpm produced far less than the available head loss. The option set, explanation, and calculator steps were corrected. Found during a PE WRE content review. | Fixed |
| May 16, 2026 | PE Civil WRE | Darcy-Weisbach Friction Factor (Q40055) | Colebrook/Moody verification for Re = 186,000 and relative roughness 0.0017 gives f ≈ 0.0235, so the closest listed answer is 0.023. The answer key and explanation were corrected. Found during a PE WRE content review. | Fixed |
| May 15, 2026 | PE Civil WRE | Partially Full Pipe Depth Ratio (Q40103) | The full-flow Manning capacity for the stated 15-inch PVC sewer was understated. Using full-pipe area and hydraulic radius gives approximately 4.60 cfs, so the flow ratio is 2.40/4.60 = 0.52 and the closest supplied hydraulic-elements row is d/D = 0.50. The answer key, explanation, and calculator steps were corrected. Reported by Joshua P. | Fixed |
| May 15, 2026 | PE Civil WRE | Hazen-Williams Head Loss (Q40047) | The answer choices did not include the head loss produced by the stated Hazen-Williams formula and inputs. The corrected computation gives approximately 3.35 ft, so the closest answer was updated to 3.4 ft and the explanation/calculator steps were rebuilt. Reported by Joshua P. | Fixed |
| May 10, 2026 | PE Civil WRE | Compound Channel — Divided Flow (Q40081) | Answer key and explanation were inconsistent with the stated compound-channel geometry. The divided-flow calculation gives approximately 280 cfs (279.8 cfs, with the imaginary vertical interfaces excluded from each subsection’s wetted perimeter), not 415 cfs, so the correct answer was changed from C to D and the solution/calculator steps were rebuilt. An earlier version of this note said 260 cfs; that value counted the interfaces as solid bank and was superseded on Sep 14, 2026. Reported by Joshua P. | Fixed |
| May 10, 2026 | PE Civil WRE | Modified Puls Routing (Q40033) | The stem referenced a storage-indication lookup but only supplied one storage-outflow point. A full lookup table and interpolation steps were added; the answer remains 48 cfs. Reported by Joshua P. | Fixed |
| May 3, 2026 | PE Civil WRE | Hydraulic Grade Line & EGL (Q40063) | The calculator steps field was incorrectly copied from a different question (pipe pressure class sizing) and bore no relation to the HGL/EGL problem. The EGL answer option was also corrected from 324.4 ft to 324.2 ft to reflect the exact computation (HGL = 323.846 ft; EGL = 323.846 + 0.388 = 324.234 ft). The explanation was updated to explicitly call out the psi → psf unit conversion (45 × 144 / 62.4). Reported by Joshua P. | Fixed |
| Apr 27, 2026 | PE Civil WRE | Open Channel Hydraulics | Answer key error in a channel-contraction specific-energy question. The explanation was also updated to correctly describe the direction of depth change in subcritical flow through a contraction. Reported by Joshua P. | Fixed |
Corrections are pushed to the live app immediately. If you are using a cached version of the app, force-refresh or clear the app cache to pick up the latest question bank.
Printed and Kindle Editions
The study app and the books are built from the same question bank, but a book cannot be updated the way the app can. When a correction affects a book that is already in print, we list it here so you can mark up your copy. Corrections are folded into the book at its next revision; Amazon does not push updates to copies already sold or already downloaded.
| Date | Affected Titles | Issue | What To Do | Status |
|---|---|---|---|---|
| Sep 14, 2026 | FE Electrical & Computer Engineering Practice Problems and the matching Kindle edition | Coherent BPSK bit error rate at Eb/N0 = 9.6 dB (Q843, printed as problem 224). The printed answer is A, 3.17 × 10−5, which is Q(4) rather than the Q-function of the computed argument. | The argument is √(2 × 100.96) = √18.24 = 4.27, and Q(4.27) ≈ 9.7 × 10−6. Of the printed options the nearest value is C, 5.0 × 10−6; the current edition of the question supplies Q(4.27) in the stem and keys C as 1.0 × 10−5. | Next printing |
| Sep 14, 2026 | FE Mechanical Engineering Practice Exams and the matching Kindle edition | Factors that directly affect the Darcy friction factor in turbulent flow (Q8373, printed as Form B problem 14, select all that apply). The printed answer selects A, B and E. | Select A and B only. The Darcy friction factor depends on the Reynolds number and the relative roughness ε/D; fluid viscosity (E) enters only through the Reynolds number and is not a direct dependency, and pipe length and density (C, D) affect the head loss, not the friction factor. | Next printing |
| Aug 25, 2026 | FE Electrical & Computer Engineering Practice Exams and the matching Kindle edition | Highest BJT current gain (Q624, printed as problem 32). The printed answer is D, “common-emitter and common-collector are equal”, and the printed solution says both have high current gain. | The answer is C, common-collector. The common-collector (emitter-follower) current gain is β + 1, while the common-emitter is β — higher by one, not equal. Common-base has a current gain below 1. The app has always keyed C. | Next printing |
| Aug 25, 2026 | FE Mechanical Practice Problems and the matching Kindle edition | Shaft and hole fit classification (Q8347, printed as problem 287). The printed answer is C, transition fit. | The answer is D, line fit. The shaft spans 50.000–50.025 mm and the hole 50.025–50.050 mm, so the minimum clearance is exactly 0.000 mm and the maximum is 0.050 mm. Clearance is never negative, which rules out a transition fit; a minimum of exactly zero is the definition of a line fit. The app has always keyed D. | Next printing |
| Aug 25, 2026 | PE Civil Structural Practice Exams and the matching Kindle edition | Plate-girder transverse stiffener requirement (Q21028, printed as problem 18). The printed answer is D, stiffeners not required. | Stiffeners are required, and the corrected answer is C. The web slenderness is h/tw = 48/0.375 = 128, while the geometric check exempts stiffeners only when h/tw ≤ 2.46√(E/Fy) = 2.46√(29,000/50) = 59.2. Because 128 far exceeds 59.2, the exemption does not apply. Corrected in the app on Aug 16, 2026. | Next printing |
| Aug 25, 2026 | PE Civil Structural Practice Exams and the matching Kindle edition | Direct-analysis notional lateral load (Q21099, printed as problem 6). The printed answer is D, 5.0 kips, which corresponds to a 0.0025 coefficient. | Use 4.0 kips, answer B. The supplied direct-analysis relation is Ni = 0.002αYi with α = 1.0 for LRFD, so for a factored story load of Yi = 2,000 kips the notional lateral load is 0.002(1.0)(2,000) = 4.0 kips. Corrected in the app on Aug 16, 2026. | Next printing |
| Aug 25, 2026 | PE Civil Water Resources & Environmental Practice Exams and the matching Kindle edition | Ductile iron pressure class selection (Q40062). The printed answer is B, which adds the 50-psi calculated surge on top of the 150-psi working pressure. | The answer is A. ANSI/AWWA C150 pressure classes already include a standard surge allowance of at least 100 psi, and the calculated surge is used only when it exceeds that allowance. Because 50 psi is below the included allowance, the class is selected on the 150-psi working pressure. Corrected in the app on Aug 15, 2026. | Next printing |
| Aug 25, 2026 | PE Civil Water Resources & Environmental Practice Exams and the matching Kindle edition | Compound-channel discharge by the divided-channel method (Q40279). The printed answer is C, 502 cfs. | Use 538 cfs, answer D. With the imaginary vertical interfaces excluded from the wetted perimeter, the main channel has P = 20 + 2(4) = 28 ft and R = 120/28 = 4.29 ft, giving 421 cfs; each floodplain carries 58.4 cfs, for 421 + 2(58.4) = 538 cfs. The app has always keyed D. | Next printing |
| Aug 24, 2026 | FE Civil Practice Problems and the matching Kindle edition | Available NPSH (Q5161). The printed keyed option is 20.7 ft, and the solution subtracts the 1.2-ft suction velocity head a second time. | Use 21.9 ft: 34 − 8 − 3.5 − 0.6 = 21.9 ft. The suction velocity head appears in both the Bernoulli suction-pressure relation and the NPSH definition, so it cancels. | Next printing |
| Aug 23, 2026 | FE Mechanical Engineering Practice Exams, FE Mechanical Practice Problems, and the matching Kindle editions | Angular velocity conversion (Q8295). The worked solution attributes the 4π/60 error to option D — but option D, 60π rad/s, is the correct answer. A reader following the printed explanation is told the right answer is a mistake. | The answer key is correct as printed: 60π rad/s ≈ 188.5 rad/s. Ignore the stated reason for option D. The wrong options are A (π rad/rev), B (4π rad/rev) and C (3π rad/rev), each in place of the standard 2π radians per revolution. | Next printing |
| Aug 23, 2026 | FE Other Disciplines Practice Exams, FE Other Disciplines Practice Problems, and the matching Kindle editions | Carnot efficiency (Q12224). Two printed distractor rationales are wrong. Option B (50%) is attributed to “equal temperatures or a miscalculation”, and option D (75%) to 1 − TC/(2TH). | The answer key is correct as printed: 62.5%. Equal reservoir temperatures give 0% efficiency, not 50% — 50% corresponds to TH = 600 K. And 1 − TC/(2TH) evaluates to 81.25%, not 75% — 75% corresponds to TH = 1,200 K. | Next printing |
| Aug 23, 2026 | FE Civil Practice Problems and the matching Kindle edition | Bending moment under a point load (Q5175). The printed explanation says option B (96.7 kip-ft) comes from swapping the distances a and b. | The answer key is correct as printed: 106.7 kip-ft. Disregard the stated reason for option B — Pab/L is symmetric in a and b, so swapping them returns the same 106.7 kip-ft. No supported calculation from the given geometry yields 96.7 kip-ft; that value would require a = 7.25 ft. | Next printing |
| Aug 23, 2026 | PE Civil Water Resources & Environmental Practice Exams and the matching Kindle edition | Earthwork shrinkage (Q40010). The printed explanation describes option B (240 yd³) as applying shrinkage to the deficit, which does not produce 240. | The answer key is correct as printed: 440 yd³. Read option B as the shrinkage loss itself, 2,000(1 − 0.88) = 240 yd³ — not the shortfall. | Next printing |
| Aug 23, 2026 | FE Other Disciplines Practice Exams and the matching Kindle edition | Energy consumption (Q12291). The printed distractor rationales are truncated to the point of being uninformative — “Option B (12.5) divides.” and “Option D uses wrong time.” | The answer key is correct as printed: 800 Wh. The specific errors are: option B divides 100 W by 8 h instead of multiplying, option C uses 1,000 W instead of 100 W, and option D uses 0.8 h instead of 8 h. | Next printing |
| Aug 12, 2026 | FE Civil Practice Exams, FE Civil Practice Problems, FE Mechanical Practice Problems, FE Other Disciplines Practice Exams, FE Other Disciplines Practice Problems, and the matching Kindle editions | Every Mohr's circle figure in these books prints its computed principal stresses and maximum shear stress on the drawing. For 20 of the 21 questions that use the figure, that means the keyed answer appears on the diagram before you solve anything. The item asking for the principal-plane angle is unaffected. | Cover the value labels below the circle before working the problem. Every question states the applied stresses in the text, so nothing is lost — the problem is fully solvable from the wording. The answer keys and worked solutions in the books are correct as printed. | Next printing |
The web app was corrected on August 12, 2026 and now shows the stress state only. If you want the corrected figures today, work these topics in the study app.
Last reviewed: August 12, 2026. Public correction notes were checked for clarity and internal-audit wording, and a printed/Kindle edition section was added.