The price of petrol (per litre) increases by 50%. By what percent should its consumption be reduced such that the expenditure on it increases by 11% only?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1, i.e., 26%.
Let initial price = 100 and initial consumption = 100
Initial expenditure = 100 × 100 = 10000
Price increases by 50% → new price = 150
Let new consumption = x
New expenditure = 150 × x
Expenditure should increase by 11% → new expenditure = 10000 × (100 + 11) ÷ 100 = 10000 × 111 ÷ 100 = 11100
So, 150 × x = 11100
⇒ x = 11100 ÷ 150 = 74
Initial consumption = 100, new consumption = 74
Reduction = (100 − 74) × 100 ÷ 100 = 26%