A farmer connects a pipe of internal diameter 25cm from a canal into a cylindrical tank in his field, which is 12m

in diameter and 2.5m deep. If water flows through the pipe at the rate of 3.6km/hr, in how much time will the tank

be filled? Also find the cost of water, if the canal department charges at the rate of Rs0.07/m3

?

R = radius of cylinder = 6m

H = height of cylinder = 2.5m

r = radius of pipe = 25/2cm =1/8m

Rate of flow of water = 3.6km/hr

In 1 hr water upto a length of 3.6km = 3600m will come out of pipe.

let the tank be filled in 'x' hrs.

volume of water coming out of pipe in x hrs = volume of cylindrical tank.

(22/7)(1/8)(1/8)(3600)(x) = (22/7)(6)(6)(2.5)

(1/8)(1/8)(3600)( x) = 6 x 6 x 2.5

3600(x) = 36 x 2.5 x 8 x 8

100(x) = 8 x 8 x 2.5

1000(x) = 8 x 8 x 25

x = 16/10 = 1.6 hrs

x = 1 hr.36 min.

Now,

cost of water = volume of cylindrical tank x 0.07

= 22/7 x 6 x 6 x 2.5 x 0.07

= Rs.19.80.

The tank will be filled in 1hr.36 min and the cost of water will be Rs.19.80.

**[ For reference-refer for-"Me n Mine CBSE Sample Papers-Page 15-google books result] **