The total surface area of a hollow metal cylinder, open at both ends of external radius 8 cm and height 10 cm is 338 p cm². Taking r to be inner radius, obtain an equation in r and use it to obtain the thickness of the metal in the cylinder.

Given,

Total surface area of hollow cylinder = 338π cm²

Height = 10 cm

External radius R = 8 cm

Let internal radius = r cm

∴ 2πRh+2πrh+2π(R²-r²) = 338π

=

=80+10r+(8+r)(8-r) =169

= 10r+64-8r+8r-r² = 89

=r²-10r+25 = 0

= r(r-5) -5(r-5) =0

= r = 5 cm

∴ Thickness of hollow cylinder = (R-r) = 8-5 = 3 cm