UPSC Prelims 2016 · CSAT
Question 77: Basic Numeracy
The average monthly income of a person in a certain family of 5 is Rs. 10,000. What will be the average monthly income of a person in the same family if the income of one person increased by Rs. 1,20,000 per year ?
AnswerUPSC’s answer is (a).
The average monthly income of 5 people is Rs 10,000, so the total is Rs 50,000 a month. One person's income rises by Rs 1,20,000 a year, which is Rs 10,000 a month. The new total is Rs 60,000 and the new average is 60,000 / 5 = Rs 12,000. Equivalently, the average rises by 10,000 / 5 = Rs 2,000. Remember: convert yearly to monthly first.
Why each option is right or wrong
- (a) Right: the average rises by Rs 2,000 to Rs 12,000.
- (b) Does not match: the average rises by only Rs 2,000.
- (c) Too large: the average rises by only Rs 2,000.
- (d) Treats the yearly rise as a monthly one.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2016, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.