Solve the problem.
-Find the critical value $\mathrm { z } _ { \alpha / 2 }$ that corresponds to a degree of confidence of 91%.
A)1.70
B)1.75
C)1.34
D)1.645

Question

Quizplus · Accepted Answer

The degree of confidence of 91% means that the area in the two tails (combined) is 9% (100% - 91%), so each tail has 4.5% (9% / 2). Looking up 4.5% in the z-table or using a calculator to find the z-value that corresponds to the cumulative area of 0.955 (since 0.5 + 0.455 = 0.955), we find the critical value $\mathrm { z } _ { \alpha / 2 }$ is approximately 1.70.

Solve the Problem zα/2\mathrm { z } _ { \alpha / 2 }zα/2​

Solve the Problem $\mathrm { z } _ { \alpha / 2 }$