Question
Let z be a random variable with a standard normal distribution, P(-1.9<=z<=2.1)
Answers
PsyDAG
I assume that you are talking about Z scores, scores in terms of standard deviations. However, I am not sure what your question is.
Possibly it would help to find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions related to those Z scores.
Possibly it would help to find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions related to those Z scores.