Quantitative Skills: Arithmetic Reasoning Under Time Pressure
What this section actually measures
Arithmetic reasoning against the clock: percentages, ratios and proportions, averages, rate–time–distance, simple algebra (solve for x), number sequences, and basic geometry (area, perimeter, angle sums). No calculator is allowed, and scratch work is expected.
Concepts to master
- Percent of versus percent change: a 25% increase multiplies by 1.25; a 25% decrease multiplies by 0.75.
- Averages: average = sum ÷ count, and therefore sum = average × count.
- Rates: rate = distance ÷ time; rearrange to time = distance ÷ rate.
- Ratios: scale both parts by the same factor before adding.
- Order of operations and solving a one-variable equation by undoing operations.
Traps that cost points
- Unit mismatch - minutes mixed with hours, cents with dollars, inches with feet.
- Averaging averages without weighting by group size.
- Reverse percentage problems: if $80 is the price after a 20% discount, the original is not $96.
- Distractors built from the most common wrong operation - adding where you should multiply, or forgetting to subtract the original value.
- Alternating number series such as +3, ×2, +3, ×2.
Rule of thumb
Write the units beside every number and cancel them before dividing. If the units left over are not the units asked for, your setup is wrong.
Worked example
A jacket costs $80 after a 20% discount. What was the original price? The price paid is 80% of the original, so 0.80 × P = 80, giving P = $100. The trap answer, $96, comes from adding 20% of $80 back onto the sale price.