For a sample of 50 firms taken from a particular industry, the mean number of employees per firm is X1 = 420:4 with s1 = 55:7. In a second industry the mean number of employees in a sample of 50 firms...

For a sample of 50 firms taken from a particular industry, the mean number of employees per firm is X1 = 420:4 with s1 = 55:7. In a second industry the mean number of employees in a sample of 50 firms is X2 = 392:5 employees with s2 = 87:9. Estimate the difference in the mean number of employees per firm in the two industries, using a 90 percent confidence interval.