[PLEASE HELP BEEN ON THIS FOR HOURS :(] Betty mixed 1 1/2 gallons of yellow paint with 2 1/2 gallons of blue paint to make green paint for her treehouse. She ran out of green and needs to make more. If she uses 4 gallons of blue paint, to keep the same ratio, how much yellow paint should Betty use?

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?