A ball is thrown up in the air from the top of a 48 ft building. The height of the ball, h(t), after t seconds is given by the equation h(t) = - 16t2 + 32 +48.
a) After how many seconds will the ball hit the ground?
b) How long does it take the ball to reach a height of 64 feet? Show the work that leads to your answer.

Assume that there is a 11% rate of disk drive failure in a year. a. if all your computer data is stored on a hard disk drive with a copy stored on a second hard disk drive, what is the probability that during a year, you can avoid catastrophe with at least one working drive? b. if copies of all your computer data are stored on four independent hard disk drives, what is the probability that during a year, you can avoid catastrophe with at least one working drive?