If the ratio between the areas of two circles is 4 : 1 then the ratio between their radii will be ?

A. 1 : 2

B. 2 : 1

C. 1 : 3

D. 4 : 1

Answer: Option B

Solution(By Examveda Team)

$$\eqalign{ & \Rightarrow \frac{{\pi R_1^2}}{{\pi R_2^2}} = \frac{4}{1} \cr & \Rightarrow \frac{{R_1^2}}{{R_2^2}} = \frac{4}{1} \cr & \Rightarrow \frac{{{R_1}}}{{{R_2}}} = \frac{2}{1}{\text{ Or }}2:1 \cr} $$