It is generally recognized as wise to back up computer data. assume that there is a 2% rate of disk drive failure in a year. a. if all of a computer's data are stored on a single hard disk drive, what is the probability that the drive will fail during a year? b. if all of a computer's data are stored on a hard disk drive with a copy stored in a second hard disk drive, what is the probability that both drives will fail during a year? c. if all of a computer's data is stored on three independent hard disk drives, what is the probability that all three will fail during a year? d. describe the improved reliability that is gained with backup drives.