Question

The radii of two right circular cylinders are in the ratio of $3:2$ and their heights are in the ratio $5:3$. Find the ratio of their curved surface areas.

• A. $C_1:C_2=5:2$
• B. $C_1:C_2=2:2$
• C. $C_1:C_2=2:5$
• D. None of these

Answer 1

The correct option is A $C_1:C_2=5:2$

We have,

$r_1:r_2=3:2$

$h_1:h_2=5:3$

We know that the curved surface area of the cylinder

$=2\pi rh$

So, the ratio of their curved surface area

$=\frac{2\pi r_1{h}_1}{2\pi r_2{h}_2}$

$=\frac{r_1{h}_1}{r_2{h}_2}$

$=\frac{r_1}{r_2}\times \frac{h_1}{h_2}$

$=\frac{3}{2}\times \frac{5}{3}$

$=\frac{5}{2}$

$=5:2$

Hence, this is the answer.