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?
- (a) A, B and C are all females.
- (b) A is the husband of D. ✓ UPSC's answer
- (c) E and F are children of D.
- (d) D is the daughter of F.
Why the answer is (b)
• A and E are sons of F and B is the son of A, so A, E and B are male. With three males and three females, C, D and F are female; F is the mother of A and E.
• D is the mother of a boy and a girl. The only boy not already accounted for as F's son is B, so D's children are B and C.
• B is the son of A and D, and there is only one married couple, so A is the husband of D, option (b).
Why the other options are wrong
- (a) A, B and C are all females.
- A and B are explicitly stated to be sons, making them male, not female.
- (c) E and F are children of D.
- E is a son of F, not a child of D, and F is the parent of A and E, not a child of D.
- (d) D is the daughter of F.
- D is female and the mother of two children, while F is the parent of A and E; D cannot be the daughter of F as F is the grandparent generation relative to B.
Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2017, held on 18 June 2017. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.