Question

(Diameter of the circle supposedly below = 20)

Joan determined that the area of the circle below is 400πcm^2. Melinda says that Joan’s solution is incorrect; she believes that the area is 100πcm^2. Who is correct and why?

Answer 1

Melinda is correct.

Explanation:

To find the area of a circle, you have to multiply the radius by the exponent. The radius is the diameter divided by 2. 20 divided by 2 is 10. 10 x 10 + 100 so it is 100

Answer 2

Melinda is correct, 100 π cm² may be the area of circle

Explanation:

It is given that, the diameter is less than 20.

Therefore radius is always less than 10 (20/2)

If radius = 10 then area = πr² = π(10)² = 100 π cm²

Therefore the maximum value of area is 100 π cm²,

it never be 400 π cm².

Joan determined that the area of the circle below is 400 π cm²

So it is false. Melinda says that Joan’s solution is incorrect; she believes that the area is 100πcm^2.

Therefore Melinda is correct, 100 π cm² may be the area of circle