Refer to the data for problem 11. Continue using the logarithms of the lengths of calls.
a. Find the F statistic and its numbers of degrees of freedom.
b. Find the critical value from the F table at the 5% level.
c. Report the result of the F test at the 5% level.
d. Summarize what this test has told you about any differences among these types of calls.

TABLE 15.5.3 Lengths of Telephone Calls Information Sales Service Other 6.3 1.2 0.6 5.1 5.2 2.9 2.6 1.2 7.0 14.2 8.4 0.6 4.4 26.6 7.4 2.5 3.0 2.6 0.8 3.8 0.4 0.6 2.2 12.3 4.2 2.8 7.0 3.9 26.7 1.2 7.7 173 7.8 4.3 3.4 1.3 2.0 7.2 2.7 3.4 13.3