SOLUTION: The standard deviation of a normal population is 10.you take a sample of 25 item from this population and compute a 95% confidence interval. In order to compute the confidence inte

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Question 1162704: The standard deviation of a normal population is 10.you take a sample of 25 item from this population and compute a 95% confidence interval. In order to compute the confidence interval, you will use?
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
sd = 10
n = 25
se = sd / sqrt(n) = 10 / sqrt(25) = 10 / 5 = 2
95% confidence interval requires two ended alpha to be equal to .05.
.05/2 means alpha os .025 on each end.
z-score required will be plus or minus the z-score that has .025 area to the left of it.
that critical z-score will be plus or minus 1.959963986
to find the associated raw score, you would need the mean.
unfortunately, the mean is missing from the problem statement.
i think the answer to your question is that you would use the standard error, otherwise known at the standard deviation of the distribution of sample means.
that's the formula i showed you above of se = sd / sqrt(n).