UPSC Prelims 2019 · CSAT
Question 55: Basic Numeracy
A family has two children along with their parents. The average of the weights of the children and their mother is 50 kg. The average of the weights of the children and their father is 52 kg. If the weight of the father is 60 kg, then what is the weight of the mother ?
AnswerUPSC’s answer is (d).
Let the children's total weight be C and the mother's weight M. Then C + M = 3 × 50 = 150 and C + father = 3 × 52 = 156. With the father at 60 kg, C = 96. So M = 150 - 96 = 54 kg. Each average is taken over three people, the two children plus one parent.
Why each option is right or wrong
- (a) Wrong: gives a children's total of 102, not 96.
- (b) Wrong: gives a children's total of 100, not 96.
- (c) Wrong: gives a children's total of 98, not 96.
- (d) Right: children 96, mother 54, average 50.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2019, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.