Why solve this alone. When you can't use a phone? Solve the equations using the phone and only keeping the numbers the include the red line under to form the final code. Ive been trying to answer this for 2 days, please help lol.

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?