2015 CSAT, all questions
UPSC Prelims 2015 · CSAT
Question 29: Logical Reasoning and Mental Ability
If A runs less fast than B, and B runs as fast but not faster than C; then, as compared to A, C runs
aslower than A
bfaster than A
cwith same speed as A
dGiven data is not sufficient to determine
AnswerUPSC’s answer is (b).
Write the speeds: A is slower than B, so A < B. B runs as fast as C but not faster, so B ≤ C. Combining, A < B ≤ C, so A < C. Therefore C runs faster than A, whether or not B and C are equal. When ordering is given with 'as fast as but not faster', treat it as 'less than or equal to'.
Why each option is right or wrong
- (a) Wrong: C cannot be slower than A, since C is at least as fast as B, who is faster than A.
- (b) Right: A < B ≤ C gives C faster than A.
- (c) Wrong: C is at least as fast as B, who already beats A.
- (d) Wrong: the chain A < B ≤ C is enough to decide.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2015, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.