A hemispherical bowl holds 2.4255 litres of water when filled level to the brim. Find its internal radius in cm. Take π = 22/7.

2.4255 litres = $2425.5{\text{cm}}^3$, and a hemisphere holds (2/3)π$r^3$, so $(2/3)(22/7)r^3=2425.5$. Then $r^3=2425.5\times 21/44=1157.625$, and since $10.5^3=1157.625,r=10.5$ cm. (Using the whole-sphere formula (4/3)π$r^3$ gives $r^3=578.81$ and $r$ ≈ 8.33 cm; 21 cm is the diameter; 5.25 cm halves the radius once too often.)