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astatsstudent
11-08-2009, 09:16 AM
I am really confused by the following question:

Here is some information that I feel is relevant from part a)
- Annual rainfall totals can be approximated by a normal distribution, with a mean of 752.4mm and a standard deviation of 105.578mm.

Part b)
The rainfall totals obtained above are a sample.
The arithmetic mean of 752.4mm is thus called a sample mean. The population mean would be calculated from an infinitely long series of annual rainfall totals. Using the sample mean, calculate a 95% confidence interval of the population mean of annual rainfall totals.
Show all of your working, & indicate whether you have used the z or t distribution and why.

If anyone may be able to point me in the right direction, I would be really thankful!

omega
11-11-2009, 10:31 AM
Do you have the sample size? If sample size is greater than 30, you can use the z distribution, otherwise use the t distribution.