Question

Find the critical value Za/2 corresponding to a 99.5% confidence level.

0.0025
2.575
2.81
1.96​

Answer 1

The critical value 2.576 corresponds to a 99.5% confidence level.

Step-by-step explanation:

The critical value 2.576 corresponds to a 99.5% confidence level. The critical value is the z-score in a standard normal probability distribution that puts an area of 0.025 in the far left tail and an area of 0.025 in the far right tail. To find the critical value, you can use a calculator, computer, or standard normal probability table.

Answer 2

The correct option is;

2.81

Step-by-step explanation:

The critical value
`Z_(\alpha /2)`, is found from the z score table as follows, where the the confidence level is 99.5

Therefore, we have α = 1 - 99.5/100 = 1 - 0.995 = 0.005

α/2 = 0.0025

The critical value is thus found from the z-score table value of 1 - 0.0025 = 0.9975

From the z-table, we can find the 0.9975 score on the row with z = 2.8 where 0.9975 can be located under the 0.1 column giving the critical value as 2.81