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Chapter 8: Discrete Probability Distributions
Figure 8-10:
Distribution with a much larger amount
of spread about the mean
The preceding figures give some examples of how the data is behaving
about their respective means. The spread about the mean gives us some idea
about the variability of the data about the mean. We will next study this
concept of variability about the mean. In particular we will study the
concepts of variance and standard deviation for a discrete random variable.
Variance
First we will define what we mean by the variance for a discrete random
variable
X
.