Do me a favor everyone: While you're waiting for an answer to your answer, go through the feed page's questions and report every info-stealing link you see. Also. Free points. Have a great rest of the day/night and thank you :)

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?