A sociologist found that in a sample of 50 retired men, the average number of jobs they had during their lifetimes was 7.2. The population standard deviation is 2.1.
a. What is the 95% confidence interval of the mean number of jobs?
b. What is the 99% confidence interval of the mean number of jobs?
Note: Not many people here feel competent enough to answer questions in Statistics. I entered some of your numbers in WolframAlpha and got some results on this page. Look at the bottom of the page under "percentile" and see if it gives meaningful answers to your question.