Two online retailers offer a particular style of webcam for sale. The prices of these cameras vary day by day. Consider two groups: Group #1 consists of consumers who purchased a camera from retailer #1 during the past three months and Group #2 consistes of consumers who purchased a camera from retailer #2 during the same period of time. A 99% confidence interval for 1−2 μ 1 − μ 2 , the difference in population mean sale prices, is 30 to 60 dollars. (b) The confidence interval provides no strong evidence to support or refute the claim that, on average, students who purchased a camera from retailer #1 spent dollars more than those who purchased a camera from retailer #2.