Reconsider Exercises 7.2.37 and 7.2.38 on time headway variability. If you haven’t done so, put the data file TimeHeadwayVariability in the Matched Pairs applet and do at least 1,000 randomizations. 

a. Use the 2SD method to determine an approximate 95% confidence interval for the mean difference in time headway variability between looking at Facebook and Instagram (Facebook – Instagram). 

b. Based on the confidence interval, is there strong evidence that there is a difference in the average time headway variability between looking at text (Facebook) and looking at pictures (Instagram) on the phone? Explain why or why not.