Noise levels at 7 manufacturing plants were measured in decibels yielding the following data:
115,149,143,105,136,157,111
Construct the 80% confidence interval for the mean noise level at such locations. Assume the population is approximately normal.
Step 1 of 4:
Calculate the sample mean for the given sample data. Round your answer to one decimal place.
Step 2 of 4:
Calculate the sample standard deviation for the given sample data. Round your answer to one decimal place
Step 3 of 4:
Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places
Step 4 of 4:
Construct the 80% confidence interval. Round your answer to one decimal place.