Outer radius of the cylindrical tube (R) = 16/2 cm = 8 cm Inner radius of the cylindrical tube (r) = (8 - 2) cm = 6 cm Length of the tube (h) = 100 cm Volume of iron used in making the cylindrical tube = πR2h - πr2h = πh(R2 - r2) = 22/7 x100(82 – 62) = 22/7 x 100 x 14 x 2 = 8800 cm3