Zelda makes herbal teas to sell. Her most popular blend is a combination of 2 kinds of mint, 80% spearmint and 20% peppermint, by weight. She buys the mint from a wholesale company. The prices she pays for each are shown in the table. What is the cost per ounce for Zelda’s mint blend?

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?