6. (TCO 7) A bank manager wanted to estimate the mean number of transactions businesses make per month ...

6. (TCO 7) A bank manager wanted to estimate the mean number of transactions businesses make per month. For a sample of 50 businesses, he found the mean number of transaction per month to be 35 and the standard deviation to be 9.5 transactions.
(a) Find a 99% confidence interval for the mean number of business transactions per month. Show your calculations and/or explain the process used to obtain the interval.
(b) Interpret this confidence interval and write a sentence that explains it. (Points : 20) 

7. (TCO 7) A company’s CEO wanted to estimate the percentage of defective product per shipment. In a sample containing 600 products, he found 45 defective products.
(a) Find a 99% confidence interval for the true proportion of defective product. Show your calculations and/or explain the process used to obtain the interval.
(b) Interpret this confidence interval and write a sentence that explains it. (Points : 20) 

8. (TCO 2) The ages of 10 students are listed in years:{ 17,20,18,24,21,26,29,18,22,28}
(a) Find the mean, median, mode, sample variance, and range.
(b) Do you think that this sample might have come from a normal population? Why or why not? (Points : 20)