The price (per litre) of petrol increases by 80%. By what percent should its consumption be reduced such that the expenditure on it increases by 17% only?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 35% .
Original price = 100 per litre
Original consumption = 100 litres
Original expenditure = 100 × 100 = 10000
Price increases by 80% → New price = 100 × 1.8 = 180
Let new consumption = x litres
Expenditure increases by 17% → New expenditure = 10000 × 1.17 = 11700
New expenditure = New price × New consumption
180 × x = 11700
x = 11700 ÷ 180 = 65
Reduction in consumption = 100 − 65 = 35 litres
Percentage reduction = (35 ÷ 100) × 100 = 35%