Suppose the proportion of sophomores at a particular college who purchased used textbooks in the past year is ps and the proportion of freshmen at the college who purchased used textbooks in the past year is pf. A study found a 90% confidence interval for $\mathrm { p } _ { \mathrm { s } } = \mathrm { pf } _ { \mathrm { f } } \text { to be } ( 0.239,0.429 )$ Does this interval suggest that sophomores are more likely than freshmen to buy used textbooks? Explain.

Question

Quizplus · Accepted Answer

The Answer is Yes. Since the interval lies entirely above 0 , there is evidence that

\mathrm { p } _ { \mathrm { S } } - \mathrm { p } _ { \mathrm { f } }

is greater than zero. In other words, there is evidence that

\mathrm { p } _ { \mathrm { S } } > \mathrm { p } _ { \mathrm { f } }

, that the proportion of sophomores who buy used used textbooks is greater than the proportion of freshmen who buy used textbooks.

Suppose the Proportion of Sophomores at a Particular College Who ps=pff to be (0.239,0.429)\mathrm { p } _ { \mathrm { s } } = \mathrm { pf } _ { \mathrm { f } } \text { to be } ( 0.239,0.429 )ps​=pff​ to be (0.239,0.429)

Suppose the Proportion of Sophomores at a Particular College Who $\mathrm { p } _ { \mathrm { s } } = \mathrm { pf } _ { \mathrm { f } } \text { to be } ( 0.239,0.429 )$