Caroline bald 20 shares of stock at 10 1/2 and after 10 months the value of the stock was 11 one fourth if caroline was to sell her shares of this stopped how much profit would she make

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?