Mental Ability and Analytical Skills
What is tested
Quick, accurate processing rather than formal logic: clock and calendar problems, ranking and order, ages, number puzzles, data sufficiency, statement–assumption and statement–conclusion, cause–effect, decision making, and Venn-diagram based counting.
Core rules
- Clocks: the minute hand gains 5.5° per minute on the hour hand. Angle = |30H − 5.5M|; if the result exceeds 180°, subtract it from 360°.
- Calendars: an ordinary year shifts the weekday by 1, a leap year by 2; the cycle repeats every 400 years.
- Ranking: if a person is nth from the left and mth from the right, total = n + m − 1.
- Data sufficiency: decide whether the data determines the answer, not what the answer is.
- Statement–conclusion: accept only what follows necessarily; a plausible inference is not a conclusion.
Worked example
What is the angle between the hands of a clock at 3:40? Hour hand = 30 × 3 + 0.5 × 40 = 90 + 20 = 110°. Minute hand = 6 × 40 = 240°. Difference = 130°, which is below 180°, so the angle is 130°. Shortcut: |30(3) − 5.5(40)| = |90 − 220| = 130°.
Traps
- Forgetting the hour hand's slow movement (0.5° per minute) and answering 120°.
- Counting both endpoints twice in ranking or queue problems.
- Treating a 'probably true' statement as a conclusion in analytical items.
- In data sufficiency, solving fully instead of merely checking sufficiency, which wastes time.