The price of petrol goes up by 10%. By how much per cent must a motorist reduce the consumption of petrol so that the expenditure on it remains unchanged?

Question

Philoid · Accepted Answer

Let the consumption of petrol = 1 unit and its cost = Rs.100

∴ New cost of 1 unit of petrol = Rs.110

Now,

Rs.110 will yield 1 unit of petrol.

∴Rs.100 will yield (1/110 × 100)

= 10/11 unit of petrol

Now,

Reduction of consumption = 1 – (10/11)

= 1/11

Percentage of reduction = (1/11 × 100) %

=