Whites varied directly as yellows cubed and inversely as purples. when there were 250 whites, there were 5 yellows and 8 purples. how many whites were there when there were 7 yellows and 4 purples

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?