UPSC Prelims 2015 · CSAT
Question 10: Basic Numeracy
An automobile owner reduced his monthly petrol consumption when the prices went up. The price-consumption relationship is as follows :
| Price (in ₹ per litre) | 40 | 50 | 60 | 75 |
| Monthly consumption (in litres) | 60 | 48 | 40 | 32 |
If the price goes up to ₹ 80 per litre, his expected consumption (in litres) will be
AnswerUPSC’s answer is (a).
Multiply price by consumption in each column: 40 × 60 = 2400, 50 × 48 = 2400, 60 × 40 = 2400, 75 × 32 = 2400. Monthly petrol spending stays fixed at ₹2,400, so consumption is inversely proportional to price. At ₹80 per litre, consumption = 2400 ÷ 80 = 30 litres. When a table looks irregular, test products and ratios first.
Why each option is right or wrong
- (a) Right: 2400 ÷ 80 = 30 litres.
- (b) Wrong: 28 litres would cost 28 × 80 = ₹2,240, not the constant ₹2,400.
- (c) Wrong: 26 litres would cost ₹2,080, not ₹2,400.
- (d) Wrong: 24 litres would cost ₹1,920, not ₹2,400.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2015, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.