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The samples in the accompanying table are observations taken from the same elements at two different times. Complete parts a and b. Click the icon to view the data table. a. Let Hd = H1 - H2- Assume that the populations are normally distributed and construct a 90% confidence interval for the difference in the means of the distribution at the times in which the samples were taken. (Round to four decimal places as needed.) X Data Table Unit Sample 1 Sample 2 12.9 3.5 17.8 8.4 20.5 12.1 VOUAWN- 13.6 4.4 18.7 11.8 16.4 7.1 12.3 5.2 Print Done