Question

Due to an increase in the price of sugar by 25%, by how much per cent must a householder decrease the consumption of sugar so that there is no increase in the expenditure on sugar?

Answer 1

Let the consumption of sugar originally be 1 unit and let its cost be Rs 100
New cost of 1 unit of sugar = Rs 125
Now, Rs 125 yield 1 unit of sugar.
∴ Rs 100 will yield $\left(\frac{1}{125}\times 100\right)$ unit = $\left(\frac{4}{5}\right)$ unit of sugar.
Reduction in consumption = $\left(1-\frac{4}{5}\right)$ = $\left(\frac{1}{5}\right)$ unit
∴ Reduction percent in consumption = $\left(\frac{1}{5}\times \frac{1}{1}\times 100\right)$ %= $\left(\frac{100}{5}\right)$ %= 20%