Final answer:
The critical value z-alpha/2 corresponds to a given level of confidence and can be found by subtracting the confidence level from 1 and dividing it by 2. It represents the number of standard deviations from the mean.
Step-by-step explanation:
The critical value z α/2 that corresponds to an 89% level of confidence can be found by subtracting the confidence level from 1 (to find α) and then dividing it by 2. The critical value represents the number of standard deviations from the mean. To calculate it, we can use a standard normal probability table or a calculator.
For example, if we want to find the critical value for a 89% confidence level, the probability α is 1 - 0.89 = 0.11. Dividing it by 2 gives us 0.055. To find the z-score that corresponds to a right tail area of 0.055, we can use a standard normal probability table or a calculator.
Once we have the critical value z α/2, we can use it to construct a confidence interval.
Learn more about confidence level here: