# A container open at the top, is in the form of a frustum of a cone of height 24 cm with radii of its lower and upper circular ends, as 8 cm and 20 cm respectively. Find the cost of milk which - Mathematics

A container open at the top, is in the form of a frustum of a cone of height 24 cm with radii of its lower and upper circular ends, as 8 cm and 20 cm respectively. Find the cost of milk which can completely fill the container. at the rate of 21 per litre. [use π=22/7]

#### Solution

Solution:
Volume of a frustum of a cone =1/3 pih(r1^2+r2^2+r1xxr2)

Volume of container =1/3 pih(R^2+r2^2+Rr)

=1/3 xx 22/7 xx 24[20xx 20 + 8 xx 8 + 20 xx 8 ]

= 15689.14 cm^3

= 15.69 litre

The cost of milk which can completely fill the container at the rate of Rs.21 per liter =Rs(21 x 15.69) = 329.49

Concept: Frustum of a Cone
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#### APPEARS IN

RD Sharma Class 10 Maths
Chapter 14 Surface Areas and Volumes
Q 67 | Page 84