Answer
1.28.
Work Step by Step
$\alpha=1-confidence \ level=1-80$%$=1-0.8=0.2.$
Hence $1-\frac{\alpha}{2}=1-0.1=0.9.$
$z_{\frac{\alpha}{2}}$ is the z score belonging to the probability of $1-\frac{\alpha}{2}=0.9$, which is 1.28.
Essentials of Statistics (5th Edition)
by Triola, Mario F.
Published by
Pearson
ISBN 10:
0-32192-459-2
ISBN 13:
978-0-32192-459-9
Chapter 7 - Estimates and Sample Sizes - 7-2 Estimating a Population Proportion - Page 331: 5
Update this answer!
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.
