UPSC Prelims 2006 · General Studies
Question 61: Logical Reasoning and Mental Ability
P, Q, R, S and T reside in a 5-storeyed (Ground + 4) building, and each of them resides on a separate floor. Further,
- 1.T does not reside on the topmost floor.
- 2.Q does not reside on the ground floor.
- 3.S resides on one storey above that of P and one storey below that of R. To know as to which of the 5 persons resides on the ground floor which of the above statements are sufficient / insufficient?
AnswerThe answer is (d).
Statement 3 puts P, S and R on three consecutive floors in that order going up. That block can sit on floors 0-2, 1-3 or 2-4 (0 is the ground). Applying statements 1 and 2 to each case: block on 0-2 gives P on the ground; block on 1-3 gives T on the ground; block on 2-4 gives T on the ground. So the ground floor can be P or T, and even all three statements together are insufficient.
- 1. Not sufficient alone or in combination: the ground floor may still be P or T.
- 2. Not sufficient alone or in combination: the ground floor may still be P or T.
- 3. It fixes only a block P, S, R of consecutive floors, not which one is the ground.
Why each option is right or wrong
- (a) With statements 1 and 3 alone, P, T or Q could still be on the ground.
- (b) With statements 2 and 3 alone, P or T could still be on the ground.
- (c) Even all three together leave P or T on the ground.
- (d) Correct: the three statements together are still insufficient.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2006, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.