A guywire is attached to a telephone pole. The pole is 30 feet tall. The wire is attached to the ground 20 feet from the base of the pole. How long does the guywire need to be

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?