A bag contains five white marbles, three green marbles, and six red marbles. What are the odds in favour of randomly picking two red marbles in the first two tries? Assume that the first marble picked is not put back into the bag

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?