the test stat is correct
next with your Ha and alpha the rejection region is .
So, your test stat is in the RR and you should reject Ho and accept Ha.
The p-value is .
Ok the question says:
Specify the critical region and calculate the test statistic based on data in the table below:
Ho: =75
Ha: < 75
alpha = .05
n = 64
=72.7
= 8.6
Here is what I have come up with, I am really confused so I'm not even sure if it's relevant.
z' = - (all over) / square root n
z' = -2.1395
With z-test I found that p = .0162
I'm not sure where to go from here or if I'm even heading in the right direction. Please and thank you for the help