What is 9+n/4=15? i will make sure you get 39 points

Which expression gives you the distance between the points (5,1)and(9,-6)

What is the total surface area of this square pyramid?

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?