Confidence level 1 a. We use the following formula to calculate a confidence interval for a mean. Calculate the sample mean ˉx from the sample data.
Therefore the Confidence Interval at a 95 confidence level is 320 to 340.
If you are interested in a CI from a single group then to calculate the confidence interval you need to know the sample size sample standard deviation and the sample arithmetic average. Therefore the Confidence Interval at a 95 confidence level is 320 to 340. To state the confidence interval you just have to take the mean or the average 180 and write it next to and the margin of error. Find a 95 CI.