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Unformatted text preview: has a countable number of different values to which the random variable can be assigned. In the two dice case this number is 11 (2,3,4,5,6,7,8,9,10,11,12). Some random variables have an uncountable number of possible values (examples are the weight of a person or length of time spent waiting) in which the possible values range continuously over the real numbers. These random variables are called continuous random variables. For the random variable of the sum of the number of dots on the top faces we obtain the following probability distribution: X 2 3 4 5 6 7 8 9 10 11 12 P(X) Expected value and variance for a Discrete Random Variable (RV) Expected Value E(X) = ∑ x p(x) Variance VAR(X) = ∑-2 ) ( μ x p(x) = 2 2 ) ( ) (-∑ x p x Example: X 1 2 3 4 P(X) .1 .3 .2 .1 .3 E(X) VAR(X)...
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- Fall '10
- Statistics, Probability theory