Posted by Thomas on .
A circle has an area of 25 pi cm^2.If a circle is drawn within that circle with a diameter equal to the radius of the first circle, what is the area of the second circle?
a. 2 1/2 pi cm^2
b. 4 1/4 pi cm^2
c. 5 1/4 pi cm^2
d. 6 1/4 pi cm^2
e. 7 1/2 pi cm^2
please answer and explain

math 
Reiny,
Since the radius of the new circle is 1/2 of the original, and the radius is squared in the area formula, the new area must be 1/4 of the original
so what is (1/4) of 25 ? 
math 
Thomas,
d. 6 1/4 pi cm^2

math 
Reiny,
correct

math 
ricardo,
The diameter of a circle is 10 meters. What is the area of the circle? (Use 3.14 for mc0041.jpg and round to the nearest tenth.)

math 
darrius,
The diameter of a circle is 10 meters. What is the area of the circle? (Use 3.14 for mc0041.jpg and round to the nearest tenth.)