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7.1 – The Normal Distribution

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The Normal Distribution, Clearly Explained!!!

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It’s also called a “bell shaped curve” because it is a

Symmetrical curve that…….wait for it…….looks like a bell.

In this example, the curve represents human height measurements.

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……Average……

…..or tall

People can be short

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You may have noticed that the curve for babies is way

tall compare to the curve for adults.

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Introduction to Normal Distributions

Lets learn the concept of normal distributions using examples like the heights of 18-year-old male students.
Mean (μ): The average value, represented as mu (μ).
Example: If the mean height is 180 cm, most students' heights will be around this value.
Graph Representation: The distribution is visualized using a frequency polygon, which shows a bell-shaped curve.

Mean Height : 180 cm

Most of the students will be clustered around 180 cm

Only a few students will have a very less height

And a few will have a more height .

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A

B

What is the difference between figure A and B ?

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A

B

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A

B

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If the mean changes then the graph is translated horizontally
If the variance changes then the graph is stretched horizontally

A small variance leads to a tall curve with a narrow centre
A large variance leads to a short curve with a wide centre

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