Question 369568
If a circle with a radius of 10 has its radius decreased by 2 , by what
percent is the area decreased?

A. 20% B. 25%C. 36% D. 40% E. none
.
Since area of any circle:
(pi)r^2
.
10 inch radius circle:
(pi)10^2 = 100(pi)
.
8 inch radius circle:
(pi)8^2 = 64(pi)
.
Decrease:
100(pi) - 64(pi) = 36(pi)
.
Percent of decrease:
[36(pi)]/[100(pi)] * 100
36/100 * 100
36%