A major department store chain is interested in estimating the average amount its credit card customers spent on their first visit to the chain's new store in the mall. Sixteen credit card accounts were randomly sampled and analyzed with the following results: ¯x = $50.50 and s = $20.
Construct a 95% confidence interval for the average amount its credit card customers spent on their first visit to the chain's new store in the mall.
1 (41.74, 59.27)
2 (32.83, 68.18)
3 (18.68, 82.32)
4 (39.84, 61.16)
5 (43.80, 57.20)
An advertising agency that serves a major radio station wants to estimate the mean amount of time that the station's audience spends listening to the radio on a daily basis. From past studies, the standard deviation is estimated as 45 minutes. What sample size is needed if the agency wants to be 95% confident of being correct to within ± 5 minutes.
1 312 audience members
2 18 audience members
3 15 audience members
4 220 audience members
5 542 station manager