Ex x xpx x 0 200 1 425 2 275 3 075

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Unformatted text preview: ion. E[X ] = x xpX (x ) = 0 × .200 + 1 × .425 + 2 × .275 + 3 × .075 + 4 × .025 = 1.3 10.6 Notes Expected Value and Variance Variance Notes The variance of a r.v. is a measure of the spread, or variability, in the r.v. The variance of a discrete r.v. X , denoted by Var (X ) is defined by Var (X ) = E[(X − µx )2 ] Random Variable (r.v.) Expected Value or 2 2 Var (X ) = E[X ] − (E[X ]) Variance 10.7 Properties of variance Expected Value and Variance Let c be a constant. Then the following hold: Var (cX ) = c 2 × Var (X ) Var (X + c ) = Var (X ) Random...
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This note was uploaded on 01/24/2014 for the course STAT 225 taught by Professor Martin during the Spring '08 term at Purdue University-West Lafayette.

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