WAEC Mathematics 2010 Paper

Concept:When water is poured into a rectangular tank, it takes the shape of the tank, so its volume equals $250 \times 120 \times h$. We convert litres to cubic centimetres using $1$ litre $= 1000$ cm$^3$.Explanation:The tank is $250$ cm long and $120$ cm wide. Let the height of the water be $h$ cm. The volume of water is $250 \times 120 \times h$ cm$^3$. Since $180$ litres are poured, volume $= 180$ litres $= 180 \times 1000 = 180000$ cm$^3$. So, $250 \times 120 \times h = 180000$. Simplify: $30000h = 180000$. Divide both sides by $30000$: $h = \frac{180000}{30000} = 6$ cm.Answer:The height of the water is $6.0$ cm, which is option A.