Describe the 95% confidence Interval for one population mean.

1. A examine at a college in the west coast reveals that, historically 45% of their students are minority students. If arbitrary samples of size 75 are selected, 80% of the samples will have less than ______% of minority students.

2. A key 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. Fifteen credit card accounts were randomly sampled and analysed with the following results:  = $50.50 and s² = 400. Concept 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 assuming that the amount spent follows a normal distribution.

1. $50.50 ± $9.09
2. $50.50 ± $10.12
3. $50.50 ± $11.00
4. $50.50 ± $11.08