Question

The area of a circular metal plate is 225pi square inches. If the radius of the plate is tripled, what will be its new area?

A. 2025pi in^2
B. 2450pi in^2
C. 3575 in^2
D. 4225 in^2

Answer 1

A. 2025pi in^2

Explanation:

If you change a linear dimension by a factor of k, the area changes by a factor of k^2.

The radius changes by a factor of 3. The area changes by a factor of 3^2 which is 9.

9 * 225pi square inches = 2025pi square inches