Test for the mean. Independent samples (Part1)
I think I figured it out. If we are dealing with one tailed test, we have to figure out is it left-tailed (rejection area on the left) or right-tailed (rejection area on the right). To reject null in left-tailed test we should have negative Z with p-value<alpha, if it is right-tailed then we should have positive Z with p-value<alpha. I don't know why it is not included in the lesson. Please, correct me if I am wrong.