Can someone me with this problem? i dont really understand it.

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?

Which shows one way to determine the facts of x3+4x2+5x+20 by grouping

What is the value of 4x to the third +4x if x is 4