The average life expectancy for Bostonians is 78.1 years (The Boston Globe, August 16, 2010). Assume that this average was based on a sample of 50 Bostonians and that the population standard deviation is 4.5 years.
a. What is the point estimate of the population mean?
b. At 90% confidence, what is the margin of error?
c. Construct the 90% confidence interval for the population average life expectancy of Bostonians.