 Hi, this is Dr. Don and I have a problem from chapter six about confidence intervals for a mean. We're given some information and we need to construct a confidence interval for a population mean. Looking at this data, the thing that jumps out at me is we're given the mean of course, but we're given sigma, the population standard deviation. Now that's a clue that we need to use the z-distribution to find this confidence interval. We'll do it using StatCrunch. I'm going to click on question help, open StatCrunch, okay I got StatCrunch open here. We'll go to stat and we want to go to z-stats, one sample with summary. We bring that up. Our sample mean is 5.7, our standard deviation is 0.8, our sample size is 41, we want to click on confidence level. They want a 90%, so I set that in there and I click compute and I get my answer here for our mean, the lower limit is 5.49, the upper limit is 5.91 rounding to two decimal places. So I hope this helps.