Which online stationery store has the best prices? An independent agency recently was asked to investigate this question. The agency randomly selected n=144 items common to each of two online stationery suppliers (labelled A and B for confidentiality) and recorded the prices charged by each. The summary results are provided below, where d¯
Which online stationery store has the best prices? An independent agency recently was asked to investigate this question.
The agency randomly selected n=144 items common to each of two online stationery suppliers (labelled A and B for confidentiality) and recorded the prices charged by each. The summary results are provided below, where d¯ is the sample mean of the difference in prices and sd is the sample standard deviation of the difference in prices:
| x¯A=2.59 | x¯B=2.09 | d¯=0.50 |
| sA=0.22 | sB=0.25 | sd=0.10 |
Assuming the data represent a matched pairs design, calculate the confidence interval for comparing mean prices using a 95% confidence level. Select the correct answer from the list below:
Hint: Inferences about a paired difference in means are covered in Section 6.5.
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