# Statistics: Confidence Intervals – Calculation – #14

Question: The national association of Independent colleges and universities reported that students graduating from public colleges and universities carry an average debt of $12,000 upon graduation. Assume that this average debt is based on sample of 245 students and that, based on past studies, the population standard deviation for the dept upon graduation is$2200.

a. Develop a 90% confidence interval estimate of the population mean.

b. Develop a 95% confidence interval estimate of the population mean.

c. Develop a 99% confidence interval estimate of the population mean.

d. Discuss what happens to the width of the confidence interval as the confidence level is increased. Does this result seem reasonable? Explain.