Plz help me with this question

Thickness = 2cm
outer diameter = 16cm = 2 outer radius
outer radius (R) = 8cm

as outer radius = inner radius + thickness
therefore inner radius = outer radius - thickness = 8 - 2 = 6cm

therefore volume of iron used = volume of outer cylinder - volume of inner cylinder

22/7 * R^2h - 22/7 * r^2h
22/7 * 100 ( 64 - 36 )
22/7 * 100 * 28
= 2200 * 4
= 8800 cm^3

therefore 8800 cm^3 of iron was used in making the cylindrical tube..