Question

question 10
the z -score boundaries for the critical region are determined by
a null hypothesis
b sample data
c alpha level
d standard error

Explanation:

In hypothesis testing, the alpha level ($\alpha$) is the probability of a Type - I error (rejecting a true null hypothesis). The critical region is the set of values for which we reject the null hypothesis. The boundaries of the critical region (in terms of z - scores) are set based on the chosen alpha level. For a two - tailed test with $\alpha = 0.05$, the critical z - scores are $\pm1.96$ because the total area in the two tails (the critical region) is $0.05$. The null hypothesis is the statement being tested, sample data is used to calculate the test statistic (not to set critical region boundaries), and the standard error is used in the calculation of the z - score (not for setting critical region boundaries).

Answer:

C. alpha level