In my stats homework there is a question where we need to construct a 95% confidence interval for the population mean and it says to assume a normal distribution. For every other question I've used 1.96 for the z (a/2) but on this one the only way to get the right answer it's using 2.26 instead. Why? I'm not copying the question cause all I need to know is in what instances you use a different number. Sorry if this makes no sense.
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Jess
2.26 is a pretty weird number for z when developing a confidence interval. Was there a sample involved and if so, did you divide the standard deviation by the sqrt n?
Otherwise, you can reverse solve and find that 2.26 has 0.0119 area in the right tail, then multiply by 2 to get 0.0238 total area in the tails which equates to 1 - 0.0238 = 0.9762 or a confidence interval of 97.62%. Again, a very weird percentage for a standard textbook problem.
Maybe there is a typo in the answer key?
Hope that helps
2.26 is a pretty weird number for z when developing a confidence interval. Was there a sample involved and if so, did you divide the standard deviation by the sqrt n?
Otherwise, you can reverse solve and find that 2.26 has 0.0119 area in the right tail, then multiply by 2 to get 0.0238 total area in the tails which equates to 1 - 0.0238 = 0.9762 or a confidence interval of 97.62%. Again, a very weird percentage for a standard textbook problem.
Maybe there is a typo in the answer key?
Hope that helps