UPSC Prelims 2014 · CSAT
Question 61: Logical Reasoning and Mental Ability
The letters L, M, N, O, P, Q, R, S and T in their order are substituted by nine integers 1 to 9 but not in that order. 4 is assigned to P. The difference between P and T is 5. The difference between N and T is 3. What is the integer assigned to N ?
AnswerUPSC’s answer is (d).
P is 4 and the difference between P and T is 5, so T is 4 + 5 = 9 (4 - 5 would be negative, which is not allowed). N differs from T by 3, so N is 9 - 3 = 6 (9 + 3 = 12 is outside 1 to 9). So N is 6. Use the range limit of 1 to 9 to throw out the second possibility in each difference.
Why each option is right or wrong
- (a) 7 differs from 9 by 2, not 3.
- (b) 5 differs from 9 by 4, not 3.
- (c) 4 is already assigned to P.
- (d) Right. 9 - 6 = 3.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2014, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.