SSC CHSL 5 Aug 2021 Shift 3 Paper

Let the price of commodity be $\mathit{₹}100$ and the consumption be 100 unit.
Hence, expenditure
$=100\times 100=10000$
According to the question,
new price $=100\times 128\%=\mathit{₹}128$
and the new expenditure
$=10000\times 112\%=\mathit{₹}11200$
$\therefore$ New consumption $=\frac{11200}{128}$
$=87.5$ unit
$\therefore$ Percentage decrease in consumption
$=\left[\frac{\left(100-87.5\right)}{100}\right]\times 100=12.5\%$