Many gas stations give a discount for paying with cash instead of a credit card. William’s local gas station gives a discount of $0.05 per gallon. He fills his car with 20 gallons of gas. How much will William save by paying cash instead of credit card?

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?