>> Basic Statistics
The 95% confidence Interval for one population mean.
1. A study at a college in the west coast reveals that, historically, 45% of their students are minority students. If random samples of size 75 are selected, 80% of the samples will have less than ______% of minority students.
2. 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. Fifteen credit card accounts were randomly sampled and analyzed with the following results= $50.50 and s2 = 400. 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 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