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# Confidence Interval: Nursing school alumi & Auditor for bank

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A nursing school wants to estimate the true mean annual income of its alumni. It randomly samples 200 of its alumi. The mean annual income was 55,200 with a standard deviation of 1,500. Find the 95% confidence inteval for the true mean annual income of the nursing school alumni.

2. An auditor wants to estimate what proportion of a bank's commercial loan files are incomplete. The auditor randomly samples 100 files and finds 9 are incomplete. Using a 95% confidence interval, estimate the true proportion of incomplete files for all the bank's commerical loans.

https://brainmass.com/statistics/confidence-interval/confidence-interval-nursing-school-alumi-auditor-bank-288305

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Hypothesis testing
A nursing school wants to estimate the true mean annual income of its alumni. It randomly samples 200 of its alumni. The mean annual income was 55,200 with a standard deviation of 1,500. find 95% confidence interval for the true mean annual income of the nursing school alumni.