Two trucks leave the truck stop at the same time, one heading north and one heading lsouth. The truck driving south is driving 15 miles per hour slower than the truck driving north. How fast is the slower truck traveling is they are 1,250 miles apart after 10 hours worth of driving?

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?