It is generally recognized that it is wise to backup computer data. Assume that there is a 3% rate of disk drive failure in a year (based on data from various sources, including lifehacker.com).

a. If you store all of your computer data on a single hard disk drive, what is the probability that the drive will fail during a year?
b. If all of your computer data are stored on a hard disk drive with a copy stored on a second hard disk drive, what is the probability that both drives will fail during a year?
c. If copies of all of your computer data are 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.