Question

Tick (✓) the correct answer:
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

(c) 4 : 3

$$\begin{gathered} \mathrm{Here}, \\ \frac{\mathrm{Total}\mathrm{surface}\mathrm{area}}{\mathrm{Lateral}\mathrm{surface}\mathrm{area}}=\frac{2\pi r(h+r)}{2\pi rh} \\ =\frac{h+r}{h} \\ =\frac{20+60}{60} \\ =\frac{4}{3} \\ =4:3 \end{gathered}$$