Question

The ratio of the radius of two sphere is 3 : 2 Then the ratio of their surface area is

• A. $4:9$
• B. $3:2$
• C. $\sqrt{3}:\sqrt{2}$
• D. $9:4$

Answer 1

Answer: (D)

$9:4$

Surface area of a sphere of radius 'r' $=4\pi r^2$
Let $r_1$ be the radius of the first sphere and $r_2$ and be the
radius of the second sphere.

Now, ratio of their surface areas is:
$S_1:S_2$
$=4\pi {r_1}^2:4\pi {r_2}^{2}h$
$={r_1}^2:{r_2}^2$
$=3^2:2^2$

$=9:4$