Use the confidence level and sample data to find a confidence
interval for estimating the population mu. Round your answer to the
same number of decimal places as the sample mean. A laboratory
tested 79 chicken eggs and found that the mean amount of
cholesterol was 249 milligrams with sigma equals 14.6 milligrams.
Construct a 95% confidence interval for the true mean cholesterol
content, mu, of all such eggs.