# Thread: Z- statistics? and how to calculate

1. ## Z- statistics? and how to calculate

We have a random sample of 200 something
with a sample average = 21
and standard deviation = 10

Can we say that the population average is greater then 14?

If we test with a signifance level = 0.01 then what value has the test statistics?

This is my thinking, because we have n>30, then we have to use the z - test?

I am calculating the value of test statistics for about 1 hour and still it's incorrect!

2. ## Re: Z- statistics? and how to calculate

Originally Posted by Nforce
We have a random sample of 200 something
with a sample average = 21
and standard deviation = 10

Can we say that the population average is greater then 14?

If we test with a signifance level = 0.01 then what value has the test statistics?

This is my thinking, because we have n>30, then we have to use the z - test?

I am calculating the value of test statistics for about 1 hour and still it's incorrect!
Yes, the z-test can be used. Follow the examples in your textbook and class notes. If you need more help, please show all your work and say where you get stuck.