UPSC Prelims 2014 · CSAT
Question 49: Basic Numeracy
As per agreement with a bank, a businessman had to refund a loan in some equal instalments without interest. After paying 18 instalments he found that 60 percent of his loan was refunded. How many instalments were there in the agreement ?
AnswerUPSC’s answer is (c).
Eighteen instalments make 60 percent of the loan, so each instalment is 60/18 percent of the loan, and the total number is 100 / (60/18) = 18 x 100 / 60 = 30. Quick check: 60 percent is three fifths, so 18 is three fifths of the total, and the total is 18 x 5 / 3 = 30. Never add instalments; scale from the known fraction.
How you could have got this
No shortcut here: in a “how many” question, ruling out options doesn’t help. Every statement has to be judged.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) 22 instalments would make 18 about 82 percent of the loan.
- (b) 24 instalments would make 18 equal to 75 percent.
- (c) Right. 18 is 60 percent of 30.
- (d) 33 instalments would make 18 about 54.5 percent.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2014, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.