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