If an object is dropped from a height of 55 feet, the function d=-16t^2 + 55 gives the height of the object after t seconds. Graph this function. Approximately how long does it take the object to reach the ground (d = 0)?

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?