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A campus book store wants to estimate the proportion of thecampus population who

ID: 2952743 • Letter: A

Question

A campus book store wants to estimate the proportion of thecampus population who own an ipod or similar device. A 90%confidence interval is constructed to estimate the true populationproporton. How large must the sample be so that the length of theconfidence interval is 0.04? A campus book store wants to estimate the proportion of thecampus population who own an ipod or similar device. A 90%confidence interval is constructed to estimate the true populationproporton. How large must the sample be so that the length of theconfidence interval is 0.04?

Explanation / Answer

z=1.65 (since prob=90%)

n=X


N=PQ(Z/E)2

=.5 .5 (1.96/.04)2 (choose .5 since thismaximizes N, since you dont know p and q)

=2401