Posted by Joe on Wednesday, September 30, 2009 at 8:37pm.
CI95 = mean + or - 1.96(sd divided by √n)
...where + or - 1.96 represents the 95% confidence interval using a z-table, sd = standard deviation, √ = square root, and n = sample size.
For the 99% confidence interval, you will have to substitute the value from a z-table that corresponds to 99%.
Put the values you are given from the problem into the formula and go from there to determine your confidence intervals.
I hope this will help get you started.
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