REE Board Exam common mistakes
REE Board Exam · Understand the traps and how to avoid them.
Computes a trigonometric, exponential-decay, or AC phasor answer with the calculator still in radian mode (or degree mode) and writes down whichever choice matches the wrong-mode number.
The REE candidate switches between calculus problems (radians) and surveying/AC problems (degrees) many times in one sitting; the mode indicator is a small symbol most people never look at, and the wrong answer almost always appears among the distractors, so nothing feels wrong.
What to do instead
Adopt a ritual: before each trig/phasor item, evaluate sin(30) and confirm it returns 0.5. If it returns -0.988, switch mode and recompute. Write the mode you used in the margin beside the computation.
Rounds intermediate results to 2-3 decimals and carries the rounded value into the next step (e.g., rounding an angle to 30.5° before taking its cosine, or rounding 1/3 to 0.33 inside a series).
Habit from hand-calculation drills and from copying intermediate values onto scratch paper; the error is invisible because every individual step looks correct.
What to do instead
Store intermediates in calculator memory (STO/RCL) or keep at least 5-6 significant digits; round only the final answer. For any item with a chain of 3+ operations, do one continuous keystroke run.
Treats an arrangement/selection problem as the other type - answers 10P3 = 720 when the question says 'a committee of 3' and wants 10C3 = 120, or vice versa for 'arranged in a row'.
The keywords are embedded in long word problems and both formulas are memorized as 'n!/(n-r)!' shapes; under time pressure the candidate pattern-matches on 'choose/select' without checking whether order matters.
What to do instead
Before computing, write one sentence: 'Does swapping two of the chosen items produce a different outcome?' Yes = permutation, no = combination. Sanity check: a combination answer is always the smaller of the two.
Finds the critical point of an optimization problem, evaluates f(c), and reports it as the maximum (or minimum) without testing the second derivative or checking the interval endpoints.
The derivative-setting step consumes most of the time, and candidates assume the exam will never ask for a boundary or inflection case; memorized procedures often omit the classification step entirely.
What to do instead
Always complete the triple check: f''(c) sign, sign change of f' around c, and f at both endpoints if the domain is closed. For 'smallest/largest possible' wording, endpoints are frequently the answer.
Substitutes the given numbers straight into a formula without converting units first - plugs horsepower where watts belong, centimeters into a meter-based formula, or lb into an equation expecting slugs/kg.
Formulas are recalled in their 'textbook' units while the item supplies data in mixed practical units (hp, rpm, cm, kg/cm², °C); conversion is treated as an optional final step rather than a precondition.
What to do instead
Convert every given quantity to SI base units in a dedicated 'given' block before writing the working equation. Handy checks: 1 hp = 746 W, 1 kg = 2.205 lb, 1 in = 2.54 cm, 1 rpm = 2π/60 rad/s.
Uses a temperature in degrees Celsius in the ideal gas law or a thermodynamic efficiency ratio (PV = nRT, η = 1 - Tc/Th) and gets an answer that is off by a large factor.
Ambient temperatures in the item are naturally written in °C, and the absolute-temperature requirement is a single word in the formula that is easy to drop when the same symbol T is used everywhere.
What to do instead
Rule: any T inside a gas law, Carnot ratio, or radiation (T⁴) expression is Kelvin. Convert immediately and write 'K' next to the number before substituting.
Adds or subtracts force/velocity/displacement magnitudes directly to get a resultant, ignoring that the vectors are not collinear (e.g., answering 50 N + 30 N = 80 N for perpendicular forces).
Arithmetic with the given numbers feels productive under time pressure, and the graphical/component method takes longer; the sum-of-magnitudes value is often planted as a distractor.
What to do instead
Whenever two given vectors are not explicitly stated as parallel, resolve into x/y components (or use R = √(A² + B² + 2AB cos θ)). Only when the angle is 0° or 180° may magnitudes be added or subtracted directly.
In a wye (Y) system, substitutes the line-to-line voltage as the phase voltage (or uses line current as phase current in delta), producing a power answer larger by a factor of 3 or √3.
The √3 factor and the Y/Δ relationships are memorized as one blended formula; the circuit diagram is read quickly and the connection type is not explicitly labeled in the working.
What to do instead
Write the connection type and the two relations at the top of the scratch work before computing: Y → V_phase = V_line/√3, I_phase = I_line; Δ → V_phase = V_line, I_phase = I_line/√3. Then use P = 3·V_phase·I_phase·pf = √3·V_line·I_line·pf.
Solves power-factor-correction items by applying the capacitor kVAR directly against the kW (or by adding angles instead of taking the difference of tangents) and reports a capacitor size that never yields the target power factor.
The candidate remembers 'kVAR = kW tan θ' but loses track of which angle belongs to the original and which to the desired condition, and lagging/leading is treated as decoration rather than as a sign.
What to do instead
Build the kVAR table explicitly: Q_old = P tan(cos⁻¹ pf_old), Q_new = P tan(cos⁻¹ pf_new), Q_cap = Q_old − Q_new, with pf as a decimal and the new pf larger than the old. Check that Q_cap > 0 and that the resulting pf is between pf_old and 1.
Reads an ampacity value from the PEC table for the conductor size and answers it directly, skipping ambient-temperature correction, conduit-fill/grouping adjustment, and the 125% continuous-load factor.
Table lookup feels like the whole problem, and the correction factors live in separate tables that are easy to forget when the item does not say 'derate' out loud.
What to do instead
Default sequence for every ampacity item: I_load × 1.25 (if continuous) → choose size → multiply tabulated ampacity by temperature correction and by conduit-fill/grouping factor → verify adjusted ampacity ≥ design load, and confirm the overcurrent device is coordinated with the conductor.