You have a coupon for a restaurant. You save $3 on a meal. What was the original cost of the meal? A drawing shows a coupon for The Pasta Bowl restaurant's grand opening, with special offer of 25 percent off.

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?