Determine the critical t-scores for each of the following conditions:

a. one-tail test, a = 0.05, and n = 21

b. two-tail test, a = 0.02, and n = 10

c. two-tail test, a = 0.05, and n = 28

d. two-tail test, a = 0.01, and n = 40 AppendixLO1