Not to be cryptic but: if you know something you are allowed to use it... except the one time I ask you to pretend you don't know something. I don't

always tell you what you know, sometimes you figure it out. Like that we have a condition that our population is normally distributed: I don't tell you that it is, but I give you histograms .. and you should be able to figure it from them.Also, everyone has different samples. If I ask for a 90% confidence mean that means one out of every ten samples won't contain the population mean ... and statistically one or more people in this class are probably not going to capture the true mean at 90%. I don't know your samples I don't know who it will be. If it is you, don' tpanic. That's statistics. You are being graded on how you interpret your results.