Can someone explain to me how to do this and give me the answer? a mail distribution center processes as many as 175,000 pieces of mail each day. the mail is sent via ground and air. each land carrier 2000 pieces per load and each air carrier 1500. the loading equipment is able to handle as many as 150 loads per day. let x be the number of loads by land carriers and y the number of loads by air carriers.

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?