There are a total of 950 boxes of shoes at a store. • Half of the boxes contain athletic shoes.
• Another 125 boxes contain dress shoes.
• Of the remaining boxes of shoes, 4 out of 5 boxes contain sandals.

Based on the expression below, how many boxes at the store contain sandals?
4(95÷2-125)÷5

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?