Question

A sphere and the base of a cylinder have equal radii. The diameter of the sphere is equal to the height of the cylinder. The ratio of the curved surface area of the cylinder and surface area of the sphere is ____.

• A. $1:1$
• B. $2:3$
• C. $3:2$
• D. $1:2$

Answer 1

The correct option is A $1:1$

Radius $=r$

height of cylinder$=2r$

CSA of cylinder$=2\pi rh=2\pi r\times 2r=4\pi r^2$

SA of sphere $=4\pi r^2$

Ratio$=\frac{4\pi r^2}{4\pi r^2}=1:1$