Question

If the diameter of circle C is 3 times greater than the diameter of circle D, the area of circle C is how many times the area of circle D?

Answer 1

The radius of circle C is also 3 times greater than the radius of circle D.
The area of circle C:
A C = (3r)² π = 9 r² π
The area of circle D:
A D = r² π
9 r² π : r ² π = 9
Answer: It is 9 times the area of circle D.