Question

In the new budget,the price of petrol has risen by 20% by how much percent must a motorist reduce the consumption of petrol so that his expenditure on it does not increase?

Answer 1

Let the price of petrol be Rs.100 per litre. Let the user use 1 litre of petrol. Therefore, his expense on petrol = 100 x 1 = Rs.100

Now, the price of petrol increases by 20%. Therefore, the new price of petrol = Rs.120.

As he has to maintain his expenditure on petrol constant, he will be spending only Rs.100 on petrol.

Let 'x' be the number of litres of petrol he will use at the new price.

Therefore, 120 x $x$ = 100
             => x = $\frac{100}{120}$
                     = $\frac{5}{6}$
                     = 0.83(approx)
He has cut down his petrol consumption by 0.17 litres 
                     = $\frac{0.17}{1} X 100$
                    = 17% REDUCTION

Answer 2

Solution:-

a= 20%

Required percentage loss = & 100+ a X1009

=> a / 100+a×100%

= > 20/100+20×100%

=> 20/120×100%

=> 16 × 2/ 3% reducing

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@GauravSaxena01