Question

Do you ever subtract using the z-score?

A) yes
B) no
C) sometimes

Answer 1

C sometimes, It seems to be completely arbitrary when one must subtract the z-score table value from 1. ... So that's great if you want the left tail of a distribution, but if you want a right tail then you need to calculate the left tail and subtract it from 1 (which is the area of the entire standard normal curve).