UPSC CDS 2 2020 Math Paper

We can say that bucket is in the form of frustum of a cone.
It is given that radii of the flat circular faces of a bucket are x and 2x.
The height of the bucket (h) = 3x
Required capacity of the bucket =

1

3

π(R2+r2+Rr)×h
=

1

3

π(x2+4x2+2x2)×3x
=

22

7

×(7x2)×x=22x3