An economics professor randomly selected 100 millionaires in the U. S. The average age of these millionaires was 52.1 years with a standard deviation of 12.3 years. What is a 95% confidence interval for the mean age, μ, of all U. S. millionaires?

The 95% confidence interval would be given by (49.66;54.54)    

Step-by-step explanation:

Information given

represent the sample mean

population mean (variable of interest)

s=12.3 represent the sample standard deviation

n=100 represent the sample size  

Confidence interval

The confidence interval for the mean is given by the following formula:

  (1)

The degrees of freedom are given by:

The Confidence is 0.95 or 95%, and the significance would be and , the critical value for this case is:

Replacing the info given we got:

The 95% confidence interval would be given by (49.66;54.54)