Question

Find the critical value zc necessary to form a confidence interval at the level of confidence shown below. c=0.80

Answer 1

Answer:

1.28

Step-by-step explanation:

Given a confidence (c) = 0.80

α = 1 - c = 1 - 0.8 = 0.2

α/2 = 0.2/2 = 0.1

From the normal distribution table, The critical value necessary to form a confidence interval is gotten by getting the z value of α/2, which is the same as that of 0.4 (0.5 - 0.1). The z value of α/2 is:

$z_\frac{\alpha}{2} =z_{0.01}=1.28$