096P The radius r in inches of a spherical balloon is related to the volume V by r V Air is pumped into the balloon so the volume after t seconds is given by r V t V t 16 14t a Find an expression for the composite function r V t To enter type pi To enter a cube root use a fractional 1 3 exponent type 3V 4T b What is the exact time in seconds when the radius reaches 12 inches