Question

The height of a hollow cylinder is $7cm$ and its radius is $3.5cm$. Then the surface area is

• A. $231{cm}^2$
• B. $154{cm}^2$
• C. $308{cm}^2$
• D. $115.5{cm}^2$

Answer 1

The correct option is A $231{cm}^2$

Given : radius $r=3.5cm$ and height $h=7cm$

Surface area of a hollow cylinder $=2\pi r(h+r)$

$=2\times 3.14\times 3.5(7+3.5)$

$=230.79c{m}^2\approx 231$

$\therefore$ Surface area $=231c{m}^2$.