Question

a cylindrical tube open at both ends is made of iron 3 cm thick if the external diameter is 42 cm and the length of the tube is 140 cm find the volume of the metal used in it

Answer 1

volume of a cylinder is given by pi(r)^2l 
where r is the radius 
and l is the length of the cylinder 
according to your question r(external) = 50/2 = 25cm 
and l = 140cm 
therefore volume of cylinder is= 3.14x(25)^2x140 
=274750cm^3 
thickness of cylindrical tube is 2cm 
therefore inner radius will be 25-2=23cm 
therefore inner volume of the cylinder will be 3.14x(23)^2x140 
=232548.4cm^3 
the volume of iron it need=274750-232548.4=42201.6cm^3l

Answer 2

Step-by-step explanation:

Answer given above is wrong