The equality of Air Canada flight times (in hours) between Vancouver and San Francisco is tested using Excel. A preliminary F test shows that there is no significant difference between the two sample variances, so, as shown in the accompanying figure (a = 0.05), the t test assuming equal variances was used.
a. Based on the displayed results below, construct a 95% confidence interval for the difference μ1 – μ2 where μ1 denotes the mean flight time from Vancouver to San Francisco. Do the confidence intervals contain 0? What can you conclude about equality of the mean flight times in both directions?
b. Use elements from the Excel display on the next page to answer these questions: At the 0.05 significance level, test the claim that flights from Vancouver to San Francisco take a longer time than flights in the other direction. What is the test statistic? What is the critical value? What is the P-value?
