#### Question

A rectangular tank is 80 m long and 25 m broad. Water flows into it through a pipe whose cross-section is 25 cm2, at the rate of 16 km per hour. How much the level of the water rises in the tank in 45 minutes.

#### Solution

Let the level of water be risen by h cm.

Then,

Volume of water in the tank = `8000xx2500xxhcm^2`

Area of cross – section of the pipe =`25cm^2`

Water coming out of the pipe forms a cuboid of base area `25cm^2` and length equal to the distance travelled in 45 minutes with the speed 16km/hour.

i.e., length=`16000xx100xx45/60cm`

∴Volume of water coming out of pipe in 45 minutes

`=25xx16000xx100(45/60)`

Now, volume of water in the tank = volume of water coming out of the pipe in 45 minutes

`⇒8000xx2500xxh=16000xx100xx45/60xx25`

`⇒h=(16000xx100xx45xx25)/(8000xx2500xx60)cm=1.5cm.`