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.