h = 2 + 32t - 16t^2 is the function given to model the balls flight and we want to know what time the ball is at 15 feet in the air, which is at 2 points in time since the ball takes a parabolic trajectory.
15 = 2 + 32t - 16t^2
0 = -16t^2 + 32t -13
since the equation isn't factorable we will use the quadratic formula.
(-b +- sqrt(b^2 - 4ac))/2a
=
we end up with t = (4+-sqrt(3))/4 which is t = 1.43 seconds and t = 0.57 seconds when approximated.