17.17 An economist is studying the average profit earned by companies in Stuttgart, Germany. Assume that Stuttgart consists of 576 companies. A simple random sample of 10 companies was selected, and each company stated down its average annual profits earned and number of sales staff in each company.

The following table shows the results.

a. Find the average annual profit earned by the companies in Stuttgart.

b. Find a 95% confidence interval for the average annual profit earned by companies in the entire city.

Sampled Company Number of Sales Staff Members Average Annual Profit (€000)

1 34 342 2 21 432 3 43 539 4 12 524 5 23 743 6 32 342 7 24 443 8 29 432 9 37 545 10 16 195