Answer:
The test statistic (z-score) of this one-mean hypothesis test is z=1.823.
Step-by-step explanation:
The null and alternative hypothesis are:
[tex]H_0: \mu=150\\\\H_a: \mu\neq 150[/tex]
The significance level is 0.05.
The sample size is n=22.
The sample mean is M=157.
The standard deviation is 18.
The z-score can be calculated as:
[tex]z=\frac{M-\mu}{\sigma/\sqrt{n}}=\frac{157-150}{18/\sqrt{22}} =\frac{7}{3.84} =1.823[/tex]
The test statistic (z-score) of this one-mean hypothesis test is z=1.823.