Which of the following is the upper critical value of z (z*) for an 80% confidence interval?

a. 1.96
b. 84
c. 2.33
d. 1.45
e. 1.28

e. 1.28

Step-by-step explanation:

We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Ztable as such z has a pvalue of . This is our critical value.

So it is z with a pvalue of , so

The correct answer is:

e. 1.28

1. d.90

2. e. none of these (80)

3. a. 0

4. b. 6

5. e. none of these (10)

6. a. 5