**Problem**

A meteorologist is inflating a spherical balloon with a helium gas. If the radius of a balloon is changing at a rate of 1.5 cm/sec., express the volume *V* of the balloon as a function of time *t* (in seconds). Hint: Use composite function relationship *V*_{sphere} = 4/3 π*r*^{3} as a function of *x* (radius), and *x* (radius) as a function of *t* (time).

A. *V*(*t*) = 5/2 π*t*^{3} |
C. *V*(*t*) = 9/2 π*t*^{3} |

B. *V*(*t*) = 7/2 π*t*^{3} |
D. *V*(*t*) = 3/2 π*t*^{3} |

**Answer Key**