Question

A hollow cylindrical tube open at both ends is made of iron 3 cm thick. If the external diameter be 56cm and the length of the tube be 182cm, find the number of cubic cm in it.

Answer 1

radius of the external cylinder (r) = 56cm / 2
= 28 cm

radius of the internal cylinder (R) = 28cm - 3 cm
= 25 cm

height of the tube = 182 cm

volume of the hollow tube = pi × r^2 × h - pi × R^2 × h
= 22/7 × 28^2 cm2 × 182 cm - 22/7 × 25^2 cm2 × 182 cm

= 28^2 cm2 - 25^2 cm2 × 182^2 cm2
= 499.7 cm3