Math Help - Confidence interval

1. Confidence interval

a sample of 10 observations is taken from a normal population for which the population standard deviation is known to be 5. the sample mean is 20.
find the 95% confidence interval for the population mean

2. Originally Posted by gogothesaint
a sample of 10 observations is taken from a normal population for which the population standard deviation is known to be 5. the sample mean is 20.
find the 95% confidence interval for the population mean
You will find several worked examples on MHF. Where are you stuck?