CBSE Class 10 Maths (Standard) 2016 · Paper 30/2/1 · Question 18

A metal container, open from the top, is in the shape of a frustum of a cone of height $21$ 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 $\text{₹}35$ per litre. $\left[\text{Use }\pi =\frac{22}{7}\right]$