Question

The price (per litre) of petrol increases by 60%. By what percent should its consumption be reduced such that the expenditure on it increases by 12% only?

• A. 70%
• B. 66%
• C. 30%
• D. 36%

Answer 1

Answer:

C. 30%

Let the original price per litre = 100
Let the original consumption = 100 litres

Original expenditure

$= 100 \times 100 = 10{,}000$

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After price increase

Price increases by 60%, so new price:
= 160

Expenditure is allowed to increase by 12%, so new expenditure:
$= 112 percentage \text{ of } 10000 = 11200$

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Let new consumption = (x) litres

$160 \times x = 11200$
$x = 70$

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Reduction in consumption

Original consumption = 100
New consumption = 70

$\text{Reduction} = 30$
$\text{Percentage reduction} = \frac{30}{100} \times 100 = 30 percentage$

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Consumption should be reduced by 30%