According to an estimate, 2 years ago the average age of all CEOs of medium-sized companies in the United States was 58 years. Jennifer wants to check if this is still true. She took a random sample of 70 such CEOs and found their mean age to be 55 years with a standard deviation of 6 years.
a. Suppose that the probability of making a Type I error is selected to be zero. Can you conclude that the current mean age of all CEOs of medium-sized companies in the Untied States is different from 58 years?
b. Using a 1% significance level, can you conclude that the current mean age of all CEOs of medium sized companies in the United States is different from 58 years? Use both approaches.