Question

Noise levels at 6 airports were measured in decibels yielding the following data:
140, 146, 137, 146, 126, 128
Construct the 80% confidence interval for the mean noise level at such locations. Assume the population is approximately normal.

(2 pts) Step 1. Calculate the sample mean for the given sample data. Round your answer to one decimal place.

            Answer: ____________________

(2 pts) Step 2. Calculate the sample standard deviation for the given sample data. Round your answer to one decimal place.

            Answer: ____________________

(2 pts) Step 3. Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.

            Answer: ____________________

(2 pts) Step 4. Construct the 80% confidence interval. Round your answer to one decimal place.

            Answer: Lower endpoint: _______________      Upper endpoint: _______________

Answer 1