Question

9. The following table gives the age (in years) of 36 randomly selected U.S. millionaires. The sample mean x−=58.53 years. Assume that the standard deviation of ages of all U.S. millionaires is 13.0 years. (See data on file: M07_Age_Millionaire_Q9.txt.)

1. Obtain a 95% confidence interval for μ, the mean age of all U.S. millionaires.

2. Interpret the confidence interval obtained in part (a).

3. According to the confidence interval obtained in part (b), could you claim that average age of all U.S. millionaires is above 55 years? Explain your answer.

4. Determine the number of millionaires should be picked to guarantee that the error of x−in estimating μ is at most 0.5 years with 98% confidence.

Answer 1