As a block of ice melts, its weight changes from 1 3/4 lb. to 1/4Ib. This change takes 1/4h. The ice melts at a constant rate. At what rate does the weight of the ice
change?

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?