Question

An open container made up of a metal sheet is in form of a frustum of a cone of height 16cm with radii of it lower and upper ends as 8cm and 20cm respectively. Find the cost of the metal used to make the container, if it costs Rs.8 per 100cm2. ( Take π = 22/7)

Answer 1

Area of metal sheet=C.S.A of frustum+pi×r2(smaller)^2
=pi×(r1+r2)(_/h^2+(r1-r2)^2)+pi×r2^2
=22÷7×28×(_/256+144)+22÷7×64
=88×20+201.14
=1760+201.14
=1961.14 cm^2
So,
Cost=8×1961.14÷100
Cost=Rs.156.8912