UPSC Prelims 2017 · CSAT
Question 55: Logical Reasoning and Mental Ability
Consider the following relationships among members of a family of six persons A, B, C, D, E and F :
- 1.The number of males equals that of females.
- 2.A and E are sons of F.
- 3.D is the mother of two, one boy and one girl.
- 4.B is the son of A.
- 5.There is only one married couple in the family at present.
Which one of the following inferences can be drawn from the above?
AnswerUPSC’s answer is (b).
Six people, three males and three females. A and E are F's sons, so they are male; B is A's son, so B is male. That makes A, E and B the three males, so C, D and F are female, and F is the mother of A and E. D is the mother of one boy and one girl: the boy can only be B, whose father is A, and the girl is C. So A and D are B's parents, and since there is only one married couple, A is D's husband.
Why each option is right or wrong
- (a) A and B are male; only C is female among them.
- (b) Correct: D's son B is also A's son, so A and D are the married couple.
- (c) E and F are A's brother and mother; D's children are B and C.
- (d) D is F's daughter-in-law (wife of F's son A), not her daughter.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2017, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.