A rectangular tank measuring 32.5 cm by 22.5 cm by 18 cm was $\frac{5}{9}$-filled with water as shown below. When Kamala poured 7 litres of water into the tank, some water overflowed. Find the volume of water that overflowed. Give your answer in litres. Ans: ___ $\ell$

1. Calculate the total capacity of the rectangular tank in cubic centimetres and convert to litres.

$\begin{aligned} \text{Total Volume} &= 32.5 \text{ cm} \times 22.5 \text{ cm} \times 18 \text{ cm} \\ &= 13162.5 \text{ cm}^3 \\ &= 13.1625 \text{ litres} \end{aligned}$

2. Determine the empty fraction and compute the remaining capacity (empty space) of the tank in litres.

$\begin{aligned} \text{Fraction of empty space} &= 1 - \frac{5}{9} = \frac{4}{9} \\ \text{Volume of empty space} &= \frac{4}{9} \times 13.1625 \text{ litres} \\ &= 5.85 \text{ litres} \end{aligned}$

3. Calculate the volume of water that overflowed.

$\begin{aligned} \text{Overflowed Volume} &= \text{Poured Volume} - \text{Volume of empty space} \\ &= 7 \text{ litres} - 5.85 \text{ litres} \\ &= 1.125 \text{ litres} \end{aligned}$