What are the critical values for a two-tailed test with a 0.01 level of significance when n is large and the population standard deviation is known?
A)Above 1.960 and below -1.960
B)Above 1.645 and below -1.645
C)Above 2.576 and below -2.576
D)Above 1.000 and below -1.000

Question

Quizplus · Accepted Answer

When n is large and the population standard deviation is known, we use a Z distribution. For a two-tailed test with a 0.01 level of significance, we divide the significance level by 2 to get the area in each tail, which is 0.005. Using a Z-distribution table, we find that the critical values for a 0.005 area in each tail are ±2.576. Therefore, the critical values for a two-tailed test with a 0.01 level of significance when n is large and the population standard deviation is known are above 2.576 and below -2.576. Option C is the only choice that matches these values.

What Are the Critical Values for a Two-Tailed Test with a 0.01