The z-table

Using Normal-Distribution Table (z-table)

How to Find Critical Region in Z-Test

Users may use this one or two tailed z-table calculator or refer the rows & columns value of standard normal distribution table to find the critical region of z-distribution.

by Using Calculator

For one one (left or right) tailed Z-test :

Supply the positive or negative value of z-score to find the rejection region right or left to the mean of normal distribution respectively.

For one two tailed Z-test :

Supply the positive & negative values of the z-score to find the rejection region at both right and left side of the mean of normal distribution.

by Using Normal-Distribution Table

Z-scores generally ranges from -3.99 to 0 on the left side and 0 to 3.99 on the right side of the mean. Refer the column & row values for z-score. The point where the row & column meets for the corresponding z-score value is the critical value of Z or the rejection area of one or two tailed z-distribution. For example the -2.95 < Z is the left tailed distribution.

To find the probability of z-score, refer the column value for -2.9 and row value for 0.05 in the negative values of standard normal distribution. The point where the column & row values met at 0.0016 is the probability or critical value of Z.

Similarly for two tailed Z-test,

-1.73 < Z < 2.25 is the two tailed distribution.

To find the probability of z-score,

Refer the column value for -1.7 and row value for 0.03 in the negative values of standard normal distribution to find the left tail. Therefore, the critical (rejection region) value of Z on left side is 0.0418

Similarly refer column value for -2.2 and row value for 0.05 in the positive values of standard normal distribution to find the right tail. Therefore, the critical (rejection region) value of Z on right side is 0.9878

Find the difference between left & right tail critical values of Z

The modulus of difference between both left & right side values is the probability of two tailed Z-score values.

The z-tale