Arithmetic, Reasoning and Analytical Ability
Domain 5 tests speed and accuracy in arithmetic and logical reasoning. Arithmetic is mostly bus-operations flavoured: distance, time, load, fare, percentage and average; reasoning covers series, coding, syllogism and seating.
Arithmetic toolkit
- Average speed = total distance ÷ total time, including stoppages.
- Percentage change = (new − old) ÷ old × 100.
- Work: if A finishes in x days, one day's work = 1/x.
- Ratio: keep units consistent before comparing.
Reasoning toolkit
- Number series: check differences, then ratios, then squares/cubes.
- Coding: map letters by position; test the same rule on all examples.
- Syllogism: draw minimal Venn diagrams; "some A are B" does not imply "some B are A" unless the statement supports conversion.
- Seating: fix one person, then place left/right using the stated facing direction.
Worked example
A bus covers 240 km at 60 km/h with four stoppages of 10 minutes each. Running time = 240 ÷ 60 = 4 hours. Stoppage time = 4 × 10 = 40 minutes. Total time = 4 h 40 min = 4.667 h. Average speed = 240 ÷ 4.667 = 51.43 km/h. The trap is to report 60 km/h, which is only the running speed.
Traps
Averaging two speeds instead of dividing total distance by total time; counting the terminal stop when the question says "in between"; changing km/h to m/s incorrectly (multiply by 5/18); and converting a syllogism's "some" into "all".