Question

Water is flowing at the rate of 15 km/hr through a pipe of diameter 14 cm into a rectangular tank which is 50 m long and 44 m wide. Find the time in which the level of water in the tank will rise by 21 cm.

• A. 5 hrs
• B. 4 hrs
• C. 3 hrs
• D. 2 hrs

Answer 1

The correct option is D

2 hrs

Let time be t hours to raise the level of the water by 21 cm.

We can equate the volume of water flow out from pipe to the volume of water in the rectangular tank.

Volume of water flow out from pipe = $\pi r^2$ (flow of water) t

Volume of water in the rectangular tank = 50 m $\times$ 44 m $\times$ 21 cm.

$\Rightarrow \frac{22}{7}\times (7cm{)}^2\times 1500000cm/hr\times t$ $=5000cm\times 4400cm\times 21cm$

$\Rightarrow t=2hr$