Find the critical value Z of α/2

1. Find Zα/2 for an 86% confidence level.
1) α = 1 – Confidence Level = 1 – 0.86 = 0.14

2. Find Zα/2 for an 86% confidence level.
1) α = 1 – Confidence Level = 1 – 0.86 = 0.14
2) α/2 = 0.14/2 = 0.07

3. Find Zα/2 for an 86% confidence level.
1) α = 1 – Confidence Level = 1 – 0.86 = 0.14
2) α/2 = 0.14/2 = 0.07
3) Draw the standard normal distribution curve.

4. Find Zα/2 for an 86% confidence level.
4) The area to the left is the complement of the area to the right, therefore
Area to the left = 1 – α/2 = 1 – 0.07 = 0.9300

5. Find Zα/2 for an 86% confidence level.
5) Look for the closest value to 0.9300 inside Table A-2 and find 0.9292 and
0.9306. The area 0.9306 is closer to 0.9300 than 0.9292. The Z-score for
0.9306 is 1.48.

6. Find Zα/2 for an 86% confidence level.
5) Look for the closest value to 0.9300 inside Table A-2 and find 0.9292 and
0.9306. The area 0.9306 is closer to 0.9300 than 0.9292. The Z-score
for 0.9306 is 1.48.
Zα/2 = 1.48