- #1

tsukuba

- 47

- 0

## Homework Statement

Let X be a normal random variable with mean 80 and standard deviation 5. What is the probability X is greater than 87? Less than 74?

I understand how to compute the z score but I'm confused as to when I have to keep the number from the z-table or subtract 1

## Homework Equations

z= x-μ /σ

## The Attempt at a Solution

z = 1.4

P (z > 87 ) = ??

I found the z score to be 0.9192 but do I keep this value as my answer or do I do 1 - 0.9192

z=-1.2

P (z < 74)= ??

again, I found z score to be .1151

So I keep this value or 1 - 0.1151 and why?

Thank you