Suppose the proportion of first year students at a particular university who purchased used textbooks in the past year is
And the proportion of second year students at the university who purchased used textbooks in the past year is
.A study found a 95% confidence interval for
-
Is (0.232,0.421).Give an interpretation of this confidence interval.
A)We are 95% confident that at this university the proportion of second year students who bought used textbooks is between 23.2% and 42.1% higher than the proportion of first year students who bought used textbooks.
B)We are 95% confident that at this university the proportion of first year students who bought used textbooks is between 23.2% and 42.1% higher than the proportion of second year students who bought used textbooks.
C)We know that 95% of first year students bought between 23.2% and 42.1% more used textbooks than second year students at this university.
D)We are 95% confident that first year students at this university bought between 23.2% and 42.1% more used textbooks than second year students.
E)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 23.2% and 42.1% higher than the proportion of second year students who bought used textbooks.

Question

Suppose the proportion of first year students at a particular university who purchased used textbooks in the past year is 
And the proportion of second year students at the university who purchased used textbooks in the past year is 
.A study found a 95% confidence interval for 
- 
Is (0.232,0.421).Give an interpretation of this confidence interval.
A)We are 95% confident that at this university the proportion of second year students who bought used textbooks is between 23.2% and 42.1% higher than the proportion of first year students who bought used textbooks. 
B)We are 95% confident that at this university the proportion of first year students who bought used textbooks is between 23.2% and 42.1% higher than the proportion of second year students who bought used textbooks. 
C)We know that 95% of first year students bought between 23.2% and 42.1% more used textbooks than second year students at this university. 
D)We are 95% confident that first year students at this university bought between 23.2% and 42.1% more used textbooks than second year students. 
E)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 23.2% and 42.1% higher than the proportion of second year students who bought used textbooks.

Quizplus · Accepted Answer

The confidence interval of (0.232, 0.421) indicates that we are 95% confident that the proportion of second year students who purchased used textbooks in the past year is between 23.2% and 42.1% lower than the proportion of first year students who purchased used textbooks in the past year. This means that it is more likely that a higher proportion of first year students purchased used textbooks than second year students. Option A and D are incorrect because they suggest that second year students purchased more used textbooks than first year students, which is not supported by the confidence interval. Option C and E are also incorrect because they make claims beyond the scope of the confidence interval, which only pertains to the difference in proportions between the two groups.

Suppose the Proportion of First Year Students at a Particular