Unformatted text preview: nother idea….
Rules for adding two (or more) random variables.
Example (just some made up, but simple, numbers):
Suppose
comes from
.
Then the expected value of
is
and the variance of is Suppose
comes from
Then the expected value of is .
is and the variance of Consider
which comes from the 12 possible sums of and values
Then the expected value of
is
and the variance is
We see that
What does and
and . .
look like? In general, there are four rules related to changing random variables:
1.
2.
3.
4.
Rule 2:
represents the original data, and
represents the data that has been multiplied by
and then had
added to it. See Class Example 3, in which we convert some Celsius temperatures to
Fahrenheit, so
and
....
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 Spring '14
 DavidStrong
 Statistics, Biostatistics, Histograms, Variance, Probability theory, probability density function

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