Given data

Cement : 12.5 kg

W.C ratio : 0.41

$\frac{\text{Water}}{\text{Cement}}=0.41$

$\frac{\text{Water}}{12.5}=0.41$

Water = 5.5 kg

Water is converted into litre

$\text {Water Quantity}= \frac{5.5 kg}{\text{Density}}=0.41$

W=5.5 litres

$=\frac{5.5 kg }{1000 kg/m^3}=5.5 \times 10^{-3} M^3$

$\therefore 1 m^3 = 1000 \ litre$

Quantity of water = $1000 \times 5.5 \times 10^{-3}$