Question

The ratio of the total surface area to the lateral surface area of a cylinder whose radius is 20 cm and height 60 cm, is

(a) 2:1

(b) 3:2

(c) 4:3

(d) 5:3

Answer 1

Radius of a cylinder (r) = 20 cm and height (h)=60 cm

$\therefore Lateralsurfacearea=2\pi rh=2\times \pi \times 20\times 60=24000\pi$

and total surface area=$2\pi rh+2\pi r^2$

$=2400\pi +2\pi \times 20\times 20=2400\pi +800\pi =3200\pi$

$\therefore Ratio3200\pi :2400\pi \Rightarrow 4:3$