## 17- 19 “Black Friday,” which occurs annually the day after Thanksgiving, is one

17- 19 “Black Friday,” which occurs annually the day after Thanksgiving, is one of the biggestshopping days of the year. During the 2012 holiday season, many stores createdcontroversy by starting their mega-sales on Thanksgiving itself. In a random sample of 25individuals who shopped during the Black Friday four-day weekend (Thursday -Sunday), the average amount spent was \$399.40 with standard deviation \$171.10. Thedata are displayed in the provided dotplot. 17. Construct and interpret a 95% confidence interval for the average amount spent byindividuals who shopped over the 2012 Black Friday weekend. Use two decimal places inyour margin of error. ________________________________________ ________________________________________ 18. Suppose we know that in a random sample of n = 22 individuals who shopped over BlackFriday weekend in 2011 the average amount spent was \$381.30 with standard deviation\$119.80. Construct and interpret a 95% confidence interval for the difference in the meanamount spent between the 2012 and 2011 Black Friday weekends. Round the margin oferror to two decimal places. Recall that for the 2012 sample of 25 individuals, theaverage amount spent was \$399.40 with standard deviation \$171.10. Dotplots of bothsamples are provided. _______________________________________ ________________________________________ 19. Suppose we know that in a random sample of n = 22 individuals who shopped over BlackFriday weekend in 2011 the average amount spent was \$381.30 with standard deviation\$119.80. Recall that for the 2012 sample of 25 individuals, the average amount spent was\$399.40 with standard deviation \$171.10. Dotplots of both samples are provided. Test, at the 5% level, if the samples provide evidence that Black Friday shoppers spentmore, on average, in 2012 than they did in 2011. Include all of the details of the test.