12 of 20 (14 complete) v Tuis Cuiz:
A metalworker has a metal alloy that is 30% copper and another alloy that is 55% copper. How many kilograms of each alloy should the metalworker combine to create 120 kg of a 50% copper alloy?
The metalworker should use kilograms of the metal alloy that is 30% copper and kilograms of the metal alloy that is 55% copper.
(Type whole numbers.)

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?