The hardness of a water sample containing

The hardness of a water sample containing $10^{-3} \mathrm{M} \mathrm{MgSO}_{4}$ expressed as $\mathrm{CaCO}_{3}$ equivalents (in ppm) is

(molar mass of $\mathrm{MgSO}_{4}$ is $120.37 \mathrm{~g} / \mathrm{mol}$ )