# Thread: Specify critical region, calculate the test stat?

1. ## Specify critical region, calculate the test stat?

Ok the question says:
Specify the critical region and calculate the test statistic based on data in the table below:
Ho: $\displaystyle \mu$ =75
Ha: $\displaystyle \mu$ < 75
alpha = .05
n = 64
$\displaystyle \bar{x}$ =72.7
$\displaystyle \sigma$ = 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' = $\displaystyle \bar{x}$ - $\displaystyle \mu$ (all over) $\displaystyle \sigma$ / 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

2. the test stat is correct
next with your Ha and alpha the rejection region is $\displaystyle (-\infty , -1.645)$.
So, your test stat is in the RR and you should reject Ho and accept Ha.
The p-value is $\displaystyle P(Z<-2.13953884)$.

3. THANK YOU! I understand now