13 compute the critical value za2 that corresponds to a 99 l

13) compute the critical value za/2 that corresponds to a 99% level of confidence.

Solution

We are finding here the critical values of z for a 2-sided test.

In that case, you express your confidence level as a decimal, add 1 to it, and divide the result by 2. Then you consult a table of the cumulative standard normal distribution to get the z value.

For a confidence level of 99%, the decimal is 0.99.

(0.99 + 1)/2 = 1.99/2 = 0.995

The z value for 0.995 is 2.58.

Thus the critical value is 2.58