BSSC CGL: Mental Ability and Reasoning for BSSC CGL

Mental Ability and Reasoning in BSSC CGL tests verbal and non-verbal reasoning through series, coding-decoding, blood relations, direction sense, analogy, classification, syllogism and figure-based questions. The section rewards pattern recognition and clean diagramming rather than calculation.

Core rules and concepts

• Letter positions: A = 1 through Z = 26; reverse positions run Z = 1 through A = 26. Coding questions often use position sums or shifts.
• Series: check first differences, then squares, cubes and primes before assuming a complex rule.
• Blood relations: draw a family tree and mark gender explicitly; do not solve in your head.
• Direction sense: track net displacement and use Pythagoras for the shortest distance.
• Syllogism: use Venn diagrams. "Some A are B" does not imply "All A are B" or "Some B are not A".

Worked example

Find the next term: 2, 6, 12, 20, 30, ? Look at the differences: 6 − 2 = 4, 12 − 6 = 6, 20 − 12 = 8, 30 − 20 = 10. The differences increase by 2, so the next difference is 12 and the next term is 30 + 12 = 42. The pattern is n(n + 1), which gives 6 × 7 = 42, confirming the answer.

Traps that cost marks

• Assuming "some A are B" automatically means "some B are not A".
• Ignoring the word "only" in syllogism statements, which changes the Venn diagram.
• Forgetting to reverse left and right after a turn in direction questions.
• Treating a letter's reverse position as its normal position in coding-decoding.