Question

A consulting agency was asked by a large insurance company
to investigate if business majors were better salespersons than those with
other majors. A sample of 20 salespersons with a business degree showed
that they sold an average of 11 insurance policies per week. Another
sample of 25 salespersons with a degree other than business showed that
they sold an average of 9 insurance policies per week. Assume that the
two populations are approximately normally distributed with population
standard deviations of 1.80 and 1.35 policies per week, respectively. Con-
struct a 99% confidence interval for the difference between the two pop-
ulation means.

Answer 1