The 15 observations in the Assignment 9 spreadsheet represent a sample of the repair times, in hours, of a complex piece of machinery.

a.Find the maximum likelihood estimates of the two parameters assuming that these data are normally distributed.

b.Using the parameters in part a, use the basic Pearson goodness-of-fit test to determine if a normal distribution is indeed a good fit assuming 95% confidence.

c.What's the probability that repair time of this piece of machinery exceeds 75 hours?

Data:

61.6 72.3 72.7 70 65.1 72.5 78.4 77.1 84.3 75.3 83.2 73 83.5 63.4 65.5