Marshall has $4000 in his bank account. It yields 8% simple interest annually. How much money in interest will the account have gained in 5 years? PLSSS HELP QUICKLY

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?