UPSC Prelims 2016 · CSAT

Question 80: Basic Numeracy

A person allows a 10% discount for cash payment from the marked price of a toy and still he makes a 10% gain. What is the cost price of the toy which is marked Rs. 770 ?

aRs. 610

bRs. 620

cRs. 630

dRs. 640

AnswerUPSC’s answer is (c).

Selling price = marked price less 10% = 0.9 x 770 = Rs 693. A 10% gain means selling price = 1.1 x cost, so cost = 693 / 1.1 = Rs 630. Check: 630 + 10% = 693. Remember: gain and loss percentages apply to cost price, while a discount applies to the marked price.

Why each option is right or wrong

(a) A 10% gain on Rs 610 gives Rs 671, not 693.
(b) A 10% gain on Rs 620 gives Rs 682.
(c) Right: 630 x 1.1 = 693 = 0.9 x 770.
(d) A 10% gain on Rs 640 gives Rs 704.

Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2016, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.