Water flows through a cylindrical pipe, whose inner radius is 1 cm, at the rate of 
in an empty cylindrical tank, the radius of whose base is 40 cm. What is the rise of water level in tank in half an hour?
Water flows in 1 sec = 80 cm
Water flows in 1/2 hour
[As 1 hour = 3600 seconds]
For cylindrical pipe,
Base radius, r = 1 cm
Height, h = water flowed in half hour = 144000 cm
As we know,
Volume of cylinder = πr2h
Where r is base radius and h is height of cylinder.
Volume of water flowed through pipe = π(1)2(144000) = 144000π cm3
For cylindrical tank,
Base radius, r = 40 cm
Let the height of water raised be h cm
As we know,
Volume of cylinder = πr2h
Where r is base radius and h is height of cylinder.
Volume of water in tank = π(40)2 h
144000π = 1600πh
h = 90 cm
Height of water raised in tank is 90 cm.