Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (±.025) and its Z score.
For 99%, use ±.005.
95% = mean ± Z SEm
SEm = SD/√n
Find the margin of error for a 95% confidence interval for estimating the population mean when the sample standard deviation equals 100, with a sample size of (i) 400, (ii) 1600. What is the effect of the sample size? (b) Find the margin of error for estimating the population mean when the sample standard deviation equals 100 for a sample size of 400, using confidence level (i) 95%, (ii) 99%. What is the effect of the choice of confidence level?
I just don't understand how to work this out. How do I put this information into an equation or a formula. If I could figure that out im pretty sure I could get the answer
please help :(
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