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**Unformatted text preview: **00% written as a proportion is 1. Therefore, the area underneath the density
curve and above the x-axis = 1.
Histogram of GPA
30 Frequency 25 20 15 10 5 0
0 3 6
g rade point average 9 12 The Normal Density Curve
A common shape of data is the bell-shaped curve. This “bell-curve” is called a normal density curve.
Data that have this shape are said to be normally distributed (or sometimes called “Gaussian distributed”,
but we won’t use that terminology in this class). Below is a picture of a normal density curve: 0.2
0.1
0.0 density 0.3 0.4 Normal Distribution -3 -2 -1 0 1 Standard Deviations from mean 2 3 Question: Describe the shape of data with a normal distribution.
Answer: Data that are normally distributed are symmetric with one mode. : Go to page 12-2 in the Lesson Book : Learn About the Properties of Normal Models (in the “do”
part, drag the flags across the curve by moving the cursor to the flags) More notes, comments, and other information:
Density curves can be described with an equation. For the nor...

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