1) a. Aldrin is a highly toxic organic compound that can cause various cancers and birth defects. Ten samples are taken from Tennessees Wolf River downstream from a toxic waste site once used by the pesticide industry gave these aldrin concentrations, in nanograms per liter:

5.17, 6.17, 6.26, 4.26, 3.17, 3.76, 4.76, 4.90, 6.57, 5.17

Find a 95% confidence interval for the average concentration of aldrin in the Wolf River. Show work by hand and by using the calculator. BEFORE ANSWERING THIS QUESTION ANSWER i AND ii BELOW.

Are you trying to calculate confidence interval of estimates for the population mean using sample data or for the sample mean using the population data?

Why does it make sense that we use a confidence interval to represent this mean?

b. A healthy amount of adrin is below 4.95 nanograms per liter. Does the data above provide significant evidence that the level of adrin is above what is considered healthy?

2) Assume that the hospital stay for women after childbirth is normally distributed with a standard deviation of 1 day. Reviewing records at her own hospital, a City Center Hospital administrator calculates that the mean hospital stay for a SRS of 81 women after childbirth is 3.5 days. Find a 98% confidence interval for the mean stay after childbirth at City Center Hospital. BEFORE ANSWERING THIS QUESTION ANSWER A AND B BELOW.

What do you notice is different about this question then question #1? So, knowing this, do you think you will be using the z-score or the t-test statistic. Explain.

Why does it still make sense that we use a confidence interval to represent this mean?