1 An economics professor randomly selected 100 millionaires

1. An economics professor randomly selected 100 millionaires in the U.S. The of these millionaires was 52.1 years with a standard deviation of 12.3 years. What 95% lower confidence limit for the mean age, mu, of all US. Millionaires?

Solution

[52.1 - 2.575*12.3/sqrt(100) , 52.1 + 2.575*12.3/sqrt(100)] = [48.93275, 55.26725] = [48.9, 55.3]