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
- (a) 30 ✓ UPSC's answer
- (b) 28
- (c) 26
- (d) 24
Why the answer is (a)
• Multiply price by consumption for each pair: 40 × 60 = 2,400; 50 × 48 = 2,400; 60 × 40 = 2,400; 75 × 32 = 2,400.
• The owner always spends ₹ 2,400 a month on petrol, whatever the price.
• At ₹ 80 per litre he will therefore buy 2,400 ÷ 80 = 30 litres — option (a).
• Hence option (a).
Why the other options are wrong
- (b) 28
- 28 litres would cost ₹ 2,240, breaking the fixed ₹ 2,400 monthly spend.
- (c) 26
- 26 litres would cost ₹ 2,080, not ₹ 2,400.
- (d) 24
- 24 litres would cost ₹ 1,920, not ₹ 2,400.
Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2015, held on 23 August 2015. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.