Q53 of 56 Page 13

In a hospital used water is collected in a cylindrical tank of diameter 2 m and height 5 m. After recycling, this water is used to irrigate a park of hospital whose length is 25 m and breadth is 20 m. If tank is filled completely then what will be the height of standing water used for irrigating the park. Write your views on recycling of water.(CBSE 2017)

Given: Height of cylindrical tank = H = 5 m

Diameter of cylindrical tank = d = 2 m


Radius of cylindrical tank = r = d/2 = 1 m


Volume of cylindrical tank = πr2H = π × (1)2 × 5 = 5π m3


Length of park = l =25 m


Breadth of park = b = 20 m


Let height of the park = h m


Volume of water in park = lbh = 25 × 20 × h = 500h m3


Now, volume of water in tank is equal to volume of water in the park.


∴ 5π = 500h


⇒ π = 100h


⇒ 3.14 = 100h


⇒ h = 0.0314 m


∴ Height of water in park = 0.0314 m


Recycling of water helps in conserving water resources and reduces wastage of water.

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