stats
posted by cindy .
A random sample of 40 men drank an average of 20 cups of coffee per week during examination final,
with the population standard deviation equal to 6 cups. A lower limit of an approximate 95% confidence
interval the population average cup of coffee is
(1) 20.000
(2) 21.859
(3) 19.708
(4) 18.141
(5) 19.051
I calculated the answer as no4?

Use the confidence level and sample data to find a confidence interval for estimating the population μ. Round your answer to the same number of decimal places as the sample mean.
A group of 64 randomly selected students have a mean score of 38.6 with a standard 9) deviation of 4.9 on a placement test. What is the 90% confidence interval for the mean score, μ, of all students taking the test?