A bucket is in the form of a frustum of a cone with a capacity of 12308.8 
of water. The radii of the top and bottom circular ends are 20 cm and 12 cm respectively. Find the height of the bucket and the area of the metal sheet used in its making. 
Volume of the frustum = 
= 12308.8
⇒ h = 15cm
Let l be the slant height of the bucket
⇒ Slant height, l = 
⇒ l = 17cm
∴ length of the bucket, l = 17cm
Curved surface area = π(r’ + r’’)l + π r’’2
= π(20 + 12)(17) + π (12)2
= 2160.32 cm2
12