Question

the volume of a metallic cylindrical pipe is 748 cm3.its length is 14 cm and its external radius is 9 cm.find its thickness.

Answer 1

Find the volume of the entire region using the 9 cm as the radius, subtract the volume of the pipe , set the answer equal to the volume of a CYLINDRICAL using the given length and pi so you can calculate the value of by applying square root which should be the radius of the pipe.. subtract that r value and the given r value and that should be the thickness of the pipe

                                 OR

The volume V is Pi . R . R . h - Pi . r . r . h where R and r are the outside and inside radii respectively, and h is the height of the pipe

so r . r = R . R - V / (Pi . h )

A quick calculation leads to r = 8 cm and the thickness is 1 cm