A hemispherical tank full of water is emptied by a pipe at the rate of `(25)/7`litres per second. How much time will it take to empty half the tank, if it is 3m in diameter?

Explanation

Here, the radius of hemisphere `= 3/2 m`

`:.` The volume of hemispherical tank in `m^3` = `2pir^3`

Volume of hemispherical tank in litres = `2pir^3**1000 = 2000pir^3`

Half of the volume of hemispherical tank in litres `= 1000pir^3`

As water is emptied at the rate of `25/7` litres per second,

`:.` Half of the tank will be emptied in time ` = (1000**22/7**3/2**3/2**3/2)/(25/7) = 8910` seconds

So, half of the tank will be emptied in `8910` seconds or `148.5` minutes.