Madhya Pradesh Police Exam Model Paper 3

Given:
Ratio of area of 2 circles = 9 ∶ 16
Formula used:
Area of circle $=\mathit{\pi }{\mathit{r}}^2$
Circumference of circle $=2\mathit{\pi }\mathit{r}$
Where,
r → Radius of circle
Calculation:
Let the radius of the circles be ‘R’ and ‘r’
∴ (Area of circle 1)/(Area of circle 2) $=9/16$
$\Rightarrow \mathit{\pi }{\mathit{R}}^2/\mathit{\pi }{\mathit{r}}^2=9/16$
$\Rightarrow {\mathit{R}}^2/{\mathit{r}}^2=9/16$
$\Rightarrow \mathit{R}/\mathit{r}=\sqrt{\left(9/16\right)}$
$\Rightarrow \mathit{R}/\mathit{r}=3/4$
(Circumference of circle 1)/(Circumference of circle 2) $=2\mathit{\pi }\mathit{R}/2\mathit{\pi }\mathit{r}$
(Circumference of circle 1) ∶ (Circumference of circle 2) = 3 ∶ 4
∴ Ratio of circumference of both the circles is 3 ∶ 4