
Answer:
a critical value of z a/2
Step-by-step explanation:
Given that the population appears to be normally distributed
Sample size of 12 is taken.
FOr hypothesis testing we have to calculate margin of error. Â Depending on the confidence level we select critical values and multiply by std error
Here though population appears to be normally distributed, we cannot take z critical value for alpha/2 since
i) sample size is very small <30
ii) Population std deviation is not known
Whenever population std deviation is not known we prefer to use t critical value instead of Z critical value.
So answer is
a critical value of z a/2