23. Tuna Fish Is there a difference in the prices of tuna, depending on the method of packaging?

Consumer Reports gives the estimated average price for a variety of different brands of tuna, based on prices paid nationally in supermarkets

Assume that the tuna brands included in this survey represent a random sample of all tuna brands available in the United States.

a. Find a 95% confidence interval for the average price for light tuna in water. Interpret this interval. That is, what does the “95%” refer to?

b. Find a 95% confidence interval for the average price for white tuna in oil. Explain why the width of this interval is different from the width of the interval in part a.

c. Find 95% confidence intervals for the other two samples (white tuna in water and light tuna in oil). Plot the four treatment means and their standard errors in a two-dimensional plot similar to Figure 8.5. How would you compare the four treatments? (We will discuss comparing more than two population means in Chapter 11.)

Transcribed Image Text:

Light Tuna In Water White Tuna White Tuna in Light Tuna In Oil Water In Oil .99 .53 1.27 1.49 2.56 .62 1.92 1.41 1.22 1.29 1.92 .66 1.23 1.12 1.19 1.27 1.30 .62 .85 .63 1.22 1.35 1.79 .65 .65 .67 1.29 1.23 .60 .69 .60 1.00 .67 .60 .66 1.27 1.28 Source: Case Study "Pricing of Tuna" Copyright 2001 by Consumers Union of U.S., Inc., Yonkers, NY 10703-1057, a nonprofit organization.