Q43 of 56 Page 13

A bucket is in the form of a frustum of a cone and it can hold 28.49 liters of water. If the radii of its circular end are 28 cm and 21 cm, find the height of the bucket. (CBSE 2012)

Here, larger circular end (R) = 28 cm, smaller circular end (r) = 21 cm

Given that, volume of bucket = 28.49 litres


Area of the frustum is,


(1/3)πh(R2 + r2 + Rr) = 28.49 l


Or (1/3)πh(R2 + r2 + Rr) = 28490 cm3 [∵, 1 litre = 1000 cm3⇒ 28.49 litres = 28490 cm3]


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Thus, the height of the bucket is 15 cm.

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