Chapter Two Day FourStandard Normal Distribution
P. 147 31,33,34,35
Homework
A Normal Distribution with:
µ = 0 and
σ = 1
Standard Normal Distribution
Using a Table to find the percent of data to the left of a specific z-score
Find the percent of data to the left of Z = 2.22
EXAMPLE
Find the percent of data to the left of z = -2.15EXAMPLE
Normalcdf (lower, upper, mean, standard deviation)
1. p(z < -2.15)
2. p(z > 2.15)
3. p (-2.15<z< 2.15)
4. P(z > -1.66)
5. 5. p(-1.66<z<2.85)
Practice – Table/Calculator
Step 2 Transform to the Normal Distribution. Use Z = (x – mean)/σ
Normalizing a Problem
Example The level of cholesterol in the blood is
important because high cholesterol levels may increase the risk of heart disease. The distribution of blood cholesterol levels in a large population of people of the same age and sex s roughly Normal. For 14-year old boys, the mean is µ = 170mg/dl. And the standard deviation is σ = 30 mg/dl. Levels above240 mg/dl may require medical attention. What percentage of 14 year old boys have more than 240 mg/dl?
Cholesterol levels of 14-year old boys who may require medical attention.