A hemispherical tank, full of water, is emptied by a pipe at the rate of 22/7 litres per second. How much time it will take to empty half the tank if the diameter of the base of the tank is 3m?

2 answers

the volume of a sphere of diameter d is π/6 d^3
so, you want to empty 1/4 of the sphere (half a hemisphere), or
π/24 * 3^3 = 9π/8 m^3 = 9000π/8 L
At a rate of π L/s, that will take 9000/8 = 1125 seconds
or 18.75 minutes
The given answer of this question is 16 min 30 sec