Question

A hemi - spherical tank full of water is emptied by a pipe at 7 litres per second . how much time will it takes to half empty the tank, if the tank is 4.2 metre diameter

Answer 1

$volume \: of \: hemisphere = \frac{2}{3} \pi {r }^{2} \\ \frac{2}{3} \times \frac{22}{7} \times 2.1 \times 2.1 \\ = 92.4 \\ 92.4 \div 2 \\ = 46.2 \\ 46.2 \div 7 \\ = 6.6$