Question

The area of two circles are in the ratio $25:36$. Then the ratio of their circumference is _________.

• A. $6:5$
• B. $3:4$
• C. $4:3$
• D. $5:6$

Answer 1

Answer: (D)

$5:6$

$A_1:A_2=25:36$

Divide by $\pi$:

$R_1^2:R_2^2=25:36$

Taking square root of both sides:

$R_1:R_2=5:6$

Multiplying by $2\pi$:

$2\pi R_1:2\pi R_2=5:6$

$C_1:C_2=5:6$