posted by Rald .
What is the rejection region for a two tailed test when a=0.05?
a. [z] > 2.575
c. [z] > 1.96
A two-tailed test of a=0.05 is equivalent to two tests of a=0.05/2=0.025 for each for the upper and lower tails.
So for |z|>1.96 has a=0.025 (two tailed) is equivalent to z>1.96 and z<-1.96.