UPSC Prelims 2015 CSAT Paper II · Q29 of 74 Logical Reasoning easy

If A runs less fast than B, and B runs as fast but not faster than C; then, as compared to A, C runs

  1. (a) slower than A
  2. (b) faster than A ✓ UPSC's answer
  3. (c) with same speed as A
  4. (d) Given data is not sufficient to determine

Why the answer is (b)

• The statement 'A runs less fast than B' establishes the inequality A < B.

• The statement 'B runs as fast but not faster than C' means B is not slower than C and not faster than C, implying B = C.

• Substituting C for B in the first inequality gives A < C.

• Therefore, C runs faster than A.

• This logical deduction confirms that option (b) is the correct answer.

Why the other options are wrong

(a) slower than A
This option contradicts the derived relationship A < C, which means C is faster, not slower, than A.
(c) with same speed as A
This option is incorrect because A is explicitly stated to run less fast than B, and since B equals C, A cannot run at the same speed as C.
(d) Given data is not sufficient to determine
The data is sufficient because the transitive property of speed comparisons allows a definitive conclusion that C is faster than A.

Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2015, held on 23 August 2015. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.

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