Question

The price (per litre) of petrol increases by 40%. By what percent should its consumption be reduced such that the expenditure on it increases by 19% only?

• A. 15%
• B. 85%
• C. 84%
• D. 18%

Answer 1

Answer:

A. 15%

Let initial price = 100 and consumption = 100
Initial expenditure = $(100 \times 100 = 10000)$

New price

Increase by 40% ⇒ New price = 140

Let new consumption = (x)

New expenditure increases by 19% ⇒
New expenditure = $(10000 \times 1.19 = 11900)$

So,

$140 \times x = 11900$

x = 85

Reduction in consumption

Original = 100, New = 85
Reduction = 15%