Peter wants to put fence around his backyard, the backyard has a form of a circle. How many feet of fence does Peter needs to buy if the backyard has a diameter of 9 feet?
Use pi= 3.14

28.26

28

29

None of the above

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?