The Professor's Response

Hi professor, I have a small question on the now you try it 7.2 problem 1
the confidence level is .99 so when I look for Z I would divide .01/2 and get .005 and look that up in the T-Table but in this particular problem we do not we simply look up .01 on the the t-table why is that?

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Professor McGukian

Hi Natasha,

We divide the alpha by two because our confidence intervals are two-sided intervals. You'll notice on your formula card, we use the notation Za/2. The alpha/2 is telling you that you must always divide alpha by two when constructing a confidence interval.

Hope that answers your question,

Professor McGuckian

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