Question

If the radius of a circle is increased by a factor of 5, the area increases by a factor of:

A:5
B:10
C:25
D:50

Answer 1

The area will be increased by 25. Option C

Explanation:

Given,

The radius of a circle is increased by 5.

To find how much the area will be increased.

Let us take,

The original radius of the circle is = r

The original area = πr²

Again,

After increasing the radius = 5r

Then the area will be = π(5r)² = 25πr²

= 25( original area)

Hence,

The area will be increased by 25.