2. The time between engine failures for a 2-1/2-ton truck used by the military is
normally distributed with a mean of 6000 miles and a standard deviation of 800
miles. What the chance that a truck will be able to travel a total distance of over
5000 miles without an engine failure? What's the chance that a fleet of a dozen
trucks will have an average time-between-failures of 5000 miles or more?