Refer to the U.S. Army Corps of Engineers study of contaminated fish in the Tennessee River (Alabama).

a. Use a random number table to generate a random sample of n = 40 observations on DDT concentration in fish from the DDT file. Compute y̅ and s for the sample measurements.

b. The Food and Drug Administration (FDA) sets the limit for DDT content in individual fish at 5 parts per million (ppm). Does the sample of part a provide sufficient evidence to conclude that the average DDT content of individual fish inhabiting the Tennessee River and its creek tributaries exceeds 5 ppm? Test using a significance level of α = .01.

c. Suppose the test of hypothesis, part b, was based on a random sample of only n = 8 fish. What are the disadvantages of conducting this small-sample test?

d. Repeat part b using only the information on the DDT contents of a sample of 8 fish (randomly selected from the 40 observations of part a). Compare the results of the large- and small-sample tests.