UPSC Prelims 1997 · General Studies
Question 131: Basic Numeracy
The average monthly income of a person in a certain family of 5 is Rs. 1000. What will be the monthly average income of a person in the same family if the income of one person increased by Rs. 12,000 per year?
AnswerThe answer is (a).
The average monthly income of 5 persons is Rs 1,000, so the total monthly income is Rs 5,000. One person's income rises by Rs 12,000 a year, that is Rs 1,000 a month, so the total becomes Rs 6,000 a month and the new average is 6,000 divided by 5, which is Rs 1,200.
Why each option is right or wrong
- (a) Right: Rs 6,000 divided by 5 is Rs 1,200.
- (b) Rs 1,600 would need a rise of Rs 3,000 a month in the total.
- (c) Rs 2,000 would need a rise of Rs 5,000 a month in the total.
- (d) Rs 3,400 treats the annual rise of Rs 12,000 as a monthly rise.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1997, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.