Question

The area of circle B is 121 times greater than the area of circle A. The radius of circle B is 44. What is the radius of circle A?

A) 2.75

B) 4

C) 44

D) 88

Answer 1

Formula:
$\bigg( \dfrac{radius_1}{radius_2} \bigg)^2 = \dfrac{area_1}{area_2}$

Plug in the values:
$\bigg( \dfrac{r}{44} \bigg)^2 = \dfrac{1}{121}$

Simplify LHS:
$\dfrac{r^2}{1936} = \dfrac{1}{121}$

Multiply by 1936 on both sides:
$r^2 = \dfrac{1936}{121}$

Simplify RHS:
$r^2 = 16$

Square root both sides:
$r = 4$

Answer: The radius is 4 units. (Answer B)