Chapter 13.7, Problem 23E

Refer to Exercise 13.7.

1. a Construct a 95% confidence interval for the mean amount of polluting effluent per gallon for plant A. If the limit for the mean amount of polluting effluent is 1.5 pound/gallon, would you conclude that plant A exceeds this limit? Why?
2. b Give a 95% confidence interval for the difference in mean polluting effluent per gallon for plants A and D. Does this interval indicate that mean effluent per gallon differs for these two plants? Why?

13.7 Four chemical plants, producing the same products and owned by the same company, discharge effluents into streams in the vicinity of their locations. To monitor the extent of pollution created by the effluents and to determine whether this differs from plant to plant, the company collected random samples of liquid waste, five specimens from each plant. The data are given in the accompanying table.

1. a Do the data provide sufficient evidence to indicate a difference in the mean weight of effluents per gallon in the effluents discharged from the four plants? Test using α = .05.
2. b Applet Exercise Find the p-value associated with the test in part (a) using the applet F-Ratio Probabilities and Quantiles.