The function g(t) gives the number of people (in millions) with email access t years aftyer 1990. Find (g(10)-g(7)) over 10-7 and interpret the meaning in context. Include correct units

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?