UPSC Prelims 2001 · General Studies

Question 145: Basic Numeracy

In 1930, a person’s age was 8 times that of his son. In 1938, the father’s age became ten times that of his son’s age in 1930. The ages of the son and father in 1940 were, respectively.

a16 years, 58 years

b15 years, 50 years

c14 years, 42 years

d13 years, 34 years

AnswerThe answer is (c).

Let the son's age in 1930 be x, so the father's was 8x. In 1938 the father is 8x + 8, which equals 10x. Hence 2x = 8 and x = 4: the son was 4 and the father 32 in 1930. In 1940 they are 14 and 42. Check: the father is 40 in 1938, which is ten times the son's age of 4 in 1930.

Why each option is right or wrong

(a) 16 and 58 do not satisfy the conditions.
(b) 15 and 50 do not satisfy the conditions.
(c) Right: 14 and 42.
(d) 13 and 34 do not satisfy the conditions.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2001, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.