91Ó°ÊÓ

How productive are U.S. workers? One way to answer this question is to study annual profits per employee. A random sample of companies in computers (I), aerospace (II), heavy equipment (III), and broadcasting (IV) gave the following data regarding annual profits per employee (units in thousands of dollars). (Source: Forbes Top Companies, edited by J. T. Davis, John Wiley and Sons.) \(\begin{array}{rrrr}\text { I } & \text { II } & \text { III } & \text { IV } \\\ 27.8 & 13.3 & 22.3 & 17.1 \\ 23.8 & 9.9 & 20.9 & 16.9 \\ 14.1 & 11.7 & 7.2 & 14.3 \\ 8.8 & 8.6 & 12.8 & 15.2 \\ 11.9 & 6.6 & 7.0 & 10.1 \\ & 19.3 & & 9.0\end{array}\) Shall we reject or not reject the claim that there is no difference in population mean annual profits per employee in each of the four types of companies? Use a \(5 \%\) level of significance.