Question

If the diameter of circle r is 30% of the diameter of circle s, the area of circle r is what percent of the area of circle s?

Answer 1

Let the radius of the circle S be r

Then area of S = pi x r²

Radius of circle R will be 30 % of r = 30r/100 = 3r/10

Area of the circle R = pi x (3r/10) ²

So Area of circle R / Area of circle S = (3/10)² = 9/100

=> Area of circle R = 9/100 x Area of circle S

=> Area of circle R = 9% of Area of circle S

So we get area of the circle R is 9% of the area of the circle S