Is n=25 or 225? Because .
Or, did you mean
Ok I am completely lost, can anyone help me out? I have done the first question, and the second one is based on it.
The first question said:
The parent distribution of x is normal with mean 80 and standard deviation 9.
Based on samples of size n=25, find the mean and standard error of the sampling distribution of .
I said: = 80
The second question is where I am lost.
It says find:
A. P(62 < x < 80)
B. P(71 < < 77)
C. x' such that P( > x') = .05
Let X be a random variable with mean and standard deviation .
Then has mean zero and standard deviation 1.
And if X was a normal random variable, then Z is a standard normal random variable and you can use your Z table.
We did that for both X and .