One of the important question for the board exam class 10 from

mensuration chapter.This question is from r d sharma class 10 maths.

chapter-16.3 question number-10 maths r d sharma,mensuration.

In this question we have to find the cost of milk at the rate of Rs.44

per litre which the container can hold given that a milk container of

height 16 cm is made of metal sheet in the form of frustum of a cone

with radii of its lower and upper ends as 8 cm and 20 cm respectively.

Given,

A milk container of the form of frustum of a cone

The radius of the lower end (r1) = 8 cm

The radius of the upper end (r2) = 20 cm

Let h be its height, h = 16 cm

Then, the capacity of the container = Volume of frustum of the cone

= 1/3 π(r22 + r12 + r1 r2 )h

= 1/3 π(202 + 82 + (20) (8) ) x 16

= 10459.42 cm3

= 10.46 litres

Now, given that cost of 1 litre of milk = Rs 44

Then the cost of 10.46 litres of milk = Rs (44 x 10.46) = Rs 460.24