Question

Plastic drum of cylindrical shape is made by melting spherical solid plastic balls of radius 1 cm.Find the number of balls required to make the drum of thickness 2 cm, height 90 cm and outer radius 30 cm.(Drum has no lid).

Answer 1

vl of ball=4.1cm sq.
no.of balls= vl of cylinder / vl of balls
(here ques can be only solved of cylinder is hollow)
outer radius = radius + thickness
so no.of balls=35060/4
=8765