A spherical balloon has a 10​-in. diameter when it is fully inflated. Half of the air is let out of the balloon. Assume that the balloon remains a sphere. a. Find the volume of the​ fully-inflated balloon.
b. Find the volume of the​ half-inflated balloon.
c. What is the radius of the​ half-inflated balloon?

a. The volume of the​ fully-inflated balloon is
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​(Simplify your answer. Type an exact​ answer, using pi as needed. Use integers or fractions for any numbers in the​ expression.)