confidence interval

#1
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
 
#3
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
Hi,

I could give you the answer, but you might want to review the following page for the explanation:
http://www.global-i-tech.co.uk/204.html

A numerical example explains step-by-step procedure here:
http://www.global-i-tech.co.uk/205.html

Hope this helps.

bbkaran