Question

A bucket is in the form of a frustum of a cone and holds 28.490 litres of water.The radii of the top and bottom are 28 cm and 21 cm respectively. Find the height of the bucket.

Answer 1

SOLUTION IS IN THE ATTACHMENT

FRUSTUM:
If the right circular cone is cut off by a plane parallel to its base then the portion of the cone between the cutting plane and the base of the cone is called a frustum of a cone.

Some Examples of frustum are: Turkish cap, bucket e.t.c

Let h be the height and r1 and r2 be the radii of the circular ends (r1>r2) of  the frustum.

Volume of the frustum = ⅓ πh ( r1² +r2² + r1r2).
HOPE THIS WILL HELP YOU..

Answer 2

volume of frustum = π / 3  h( r² + R² + r R ) 

π / 3  h( r² + R² + r R ) = 28.490 l 

π / 3  h( r² + R² + r R ) = 28490 cm³

3.14 / 3 x h ( 21² + 28² + 21 x 28 ) = 28490 

1.046 x h( 441 + 784 + 588) = 28490 

1.046 x h x 1813   = 28490 

h = 28490 / 1.046 x 1813 

h = 28490  / 1896.398

h = 15.02 cm