Question

the thickness of metal pipe is 1.5cm. its diameter (inner) is 21cm. Find the volume of metal required for pipe of length 7cm?

Answer 1

perimeter is 66 cm so the volume is 66*1.5*7=693 cube cm

Answer 2

Inner diameter =21cm
Radius=21/2 cm
So, area =(22/7)×(21/2)×(21/2)=346.5

Outer diameter=24cm
Radius=12cm
So,area=(22/7)×12 ×12=452.57

So, area of the ring=106.07
Volume of the pipe=106.07×7=742.49