01.13.4
S
Brass is made from a mixture of copper and other elements. A mixture that is 80% copper is combined with a mixture that is
60% copper, resulting in 100 pounds of brass that is 65% copper.
Which equation can be used to find x, the amount of 60% mixture used to create the 65% mixture?

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?