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**Unformatted text preview: **mal density curve, the equation is: f(x)= 1
σ 2π e 1 x-µ - 2 σ 2 . Question: I don’t expect you to memorize this equation – thank goodness!! But, what two
common parameters do you notice in this equation?
Answer: the mean ( µ ) and standard deviation ( σ ).
Therefore, all normal density curves can be described by the mean and standard deviation of
the data set. In the normal curve above, the mean is 0 and the standard deviation is 1. As mentioned in the
ActivStats tutorial, when a normal curve has a mean = 0 and standard deviation = 1, it is called a
standard normal curve.
The mean describes the location of the curve (where the center of the curve will be on the xaxis). The standard deviation describes the spread (variability) of the curve. Some examples are given below.
Normal Distribution Normal Distribution 0.12 st dev = 3 in. density 0.06 mean = 90 in. 0.06 0.08 0.08 mean = 70 in. 0.02 0.02 0.04 0.04 mean = 80 in. st dev = 9 in. st dev = 12 in. 0.0 0.0 density mean = 70 i...

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