3. For a certain type of computer, the length of time between charges of the battery is normally distributed with a mean of 5.0 hours and a standard deviation of 1.5 hours.

a.. If one of these computers is randomly selected, what is the probability the length of time between charges is between 5.0 and 7.0 hours?

b. What is the minimum time a computer battery would have to last to be in the top 8% of length of time between charges?

c. Suppose a sample of 60 such computers was randomly chosen. What is the sampling distribution of the sample mean x?