The number of breakdowns for a university computer system is closely monitored by the director of the computing center, because it is critical to the efficient operation of the center. The number averages 4 per week, with a standard deviation of 0.8 per week.
a Find an interval that must include at least 90% of the weekly figures on number of breakdowns.
b The center director promises that the number of breakdowns will rarely exceed 8 in a one week period. Is the director safe in making this claim? Why or why not?