A survey of randomly selected university students found that 94 of the 109 first-year students and 96 of the 142 second-year students surveyed had purchased used textbooks in the past year. of (a) Construct a 95% confidence interval for the difference in the proportions of first-year and second-year university students who purchased used textbooks. (Round your answers to 4 decimal places, if needed.) Answer: ( (b) If a 98% confidence interval for the difference in proportion of first-year and second-year university students who purchased used textbooks is (0.067, 0.3056). Give an interpretation of this confidence interval. We are 98% confident that the first-year students at this university bought between 6.7% and 30.56% more used textbooks than second-year students. We know that 98% of the first-year students bought between 6.7% and 30.56% higher than the proportion of second-year students who bought used textbooks. We are 98% confident that, at this university, the proportion of second-year students who bought used textbooks is between 6.7% and 30.56% higher than the proportion of first-year students who bought used textbooks. We are 98% confident that, at this university, the proportion of first-year students who bought used textbooks is between 6.7% and 30.56% higher than the proportion of second-year students who bought used textbooks. We know that 98% of all random samples done on the population will show that the proportion of first-year students who bought used textbooks is between 6.7% and 30.56% higher than the proportion of second-year students who bought used textbooks. Check Last saved at 17:57:29