UPSC Prelims 1998 · General Studies
Question 142: Basic Numeracy
In a family, a couple has a son and a daughter. The age of the father is three times that of his daughter and the age of the son is half of his mother. The wife is nine years younger to her husband and the brother is seven years older than his sister. What is the age of the mother?
AnswerThe answer is (d).
Let the daughter be d years old. Her brother is d + 7, and the mother is twice the son's age, 2(d + 7). The father is 3d, and the mother is nine years younger, so 3d - 9 = 2d + 14, giving d = 23. The son is 30, the mother 2 x 30 = 60 and the father 69. Check: 69 - 9 = 60.
Why each option is right or wrong
- (a) 40 makes the son 20 and the daughter 13, so the father is 39 by one rule and 49 by the other.
- (b) 45 gives a father of 54 but a daughter of 15.5, whose triple is 46.5.
- (c) 50 gives a father of 59 but a daughter of 18, whose triple is 54.
- (d) Right: mother 60, father 69, daughter 23, son 30.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1998, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.