Question

If the price of cooking gas increases by 36%, by what percent should a family decrease its consumption
of cooking gas, so that their expenditure on cooking gas remains same as earlier?

Answer 1

Let the price = P and the consumption = C

Total expenditure = P x C

If the price increases by 36%  =  1.36 P

To maintain expenditure at P x C,

Consumption  =  $\frac{P * C}{1.36 P}$  =  $\frac{C}{1.36}$  =  0.74 C

% reduction in consumption  =  $\frac{C - 0.74 C}{C}$ X 100  =  $\frac{0.26 C}{C}$ X 100  =  26%