A survey of randomly selected university students found that 90 of the 107 first-year students and 95 of the 142 second-year students surveyed had purchased used textbooks in the past year. (a) Construct a 90% 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.) (b) If a 95% confidence interval for the difference in proportion of first-year and second-year university students who purchased used textbooks is (0.0682, 0.276). Give an interpretation of this confidence interval.