A survey of randomly selected university students found that 94 of the 108 first-year students and 98 of the 141 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 (0.0764,0.2743). Give an interpretation of this confidence interval.
a. We know that 95% of all random samples done on the population will show that the proportion of first-year students who bought used textbooks is between 7.64% and 27.43% higher than the proportion of second-year students who bought used textbooks.
b. We know that 95% of the first-year students bought between 7.64% and 27.43% higher than the proportion of second-year students who bought used textbooks.
c. We are 95% confident that the first-year students at this university bought between 7.64% and 27.43% more used textbooks than second-year students.
d. We are 95% confident that, at this university, the proportion of first-year students who bought used textbooks is between 7.64% and 27.43% higher than the proportion of secondyear students who bought used textbooks.
e. We are 95% confident that, at this university, the proportion of second-year students who bought used textbooks is between 7.64% and 27.43% higher than the proportion of first-year students who bought used textbooks.