The area of a circle is increased by 1500%. By what percent has the radius of the circle increased?	Pick:
A) 100%
B) 200%
C) 300%
D) 600%
E) 800%
The area of the circle is increased by 1500%, thus the area is increased 16 times.   The area of a circle it proportional to the square of the radius (area=πr^2), therefore the radius must increase 4 times (diameter increase 4 times = area increase 16 times), which is increase by 500%.   Answer: 300%
<result>C</result>
The area of a circle is increased by 1500%. By what percent has the radius of the circle increased?