The project manger of a software company requested an analysis of past performance. The assigned analyst compared actual labor with the initial estimate for 20 most recent projects. The results are X=actual-initial estimate (in thousands of hours) are as follows
15.2 7.2 0.1 10.9 2.5 14.1 4.8 -2.8 7.4 12.5
8.3 9.1 10.2 5.1 -4.2 6.0 13.2 3.8 18.1 5.5
a. Select an appropriate probability distribution and why
b. If X has a normal probability distribution what is the population mean and standard deviation
c. How musch would the estimate need to be changed so that there is a 50% chance of an overrun