Normal

Question 1

State the normal “rules”

Answer 1

• 68 (z=1), 95 (z=2), 99.7 (z=3)
• Area under the curve is 1.0

Question 2

What do the following give you?

1. dnorm
2. pnorm
3. qnorm

Answer 2

1. Density for value
2. Cumulative normal probability (left to right)
3. X for the cumulative probability

Question 3

What are z-scores?

Answer 3

• Tell you how many SD the x is from the mean
• z = value - mean / SD