Question

a hemisphereical tank full of water is emptied 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

Answer 1

Diameter given = 3m = 300 cm

=> radius( r) = 300/2 cm = 150 cm

Volume of water = volume of hemisphere = 2/3pi r^3

= 2/3 * pi * 150*150*150

Half of the volume = (1/3 * pi * 15 * 15 * 15 * 1000) cu cm

= (2475 * 10^4) /7 cucm

Since 1000 cu cm = 1 litre

=> (2475*10^4) /7 cu cm = 2475*10^4) / 7000

= 24750/7 litre

Since , 25/7 litre is emptied in 1 second

24750/7 litre will be emptied in(24750*7)/25*7 seconds

=990 seconds

= 16 min 30 sec