Question: A marketing research firm wishes to compare the prices charged by two supermarket chains. The research firm using a standard shopping list of ten identical purchases at ten of each of the chains stores. The stores for each chain are randomly selected and the data is below:

Chain #A Chain #B

119.25 111.99
123.71 116.62
121.32 114.88
121.72 115.38
122.34 115.11
122.42 114.40
120.14 117.02
123.63 113.91
122.19 116.89
122.43 111.87

a. Consider these samples as random samples and two tailed test to test the difference of two means. Determine your null and alternative hypothesis. Use a pooled standard deviation. (Hint: Minitab can do all the tedious calculations for you. Input your two columns of data into the Minitab worksheet; Go to Stats, then basic stats; under basic stats click on two sample t and continue.)

b. Test using alphas of .10, .05,.01 and .001.

c. Compute a 95% confidence interval for the difference of two means. Again, you can get the interval from your output.