Sally has been measuring the tree in her yard for a science project. the tree has grown 1/2 of an inch each month and gotten a total of 2 inches taller. how many months has sally been measuring this tree?

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?