Luna want to know what proportion of the 7th graders at her school are interested in taking art class. which is the best group survey to find this information. a: ask all of her classmates in her homeroom who show up for school one day? b: ask every person who is waiting at her bus stop one afternoon. c: ask every 12th person who leaves school one afternoon. roll dice to determine which person to ask first. d: ask all her friends to ask their friends.

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?