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Unformatted text preview: Chapter 8.1: Random Variables A random variable assigns a number to each outcome of an exper iment. We use a random variable when we have an experiment where the outcomes may be counted or measured. Suppose two dice are rolled. Let the random variable X denote the sum of the rolls. 2 nd roll 1 st roll 1 2 3 4 5 6 1 2 3 4 5 6 7 2 3 4 5 6 7 8 3 4 5 6 7 8 9 4 5 6 7 8 9 10 5 6 7 8 9 10 11 6 7 8 9 10 11 12 We can see that the rolls can have a sum of 2 , 3 , . . . , 12. Thus, X can take on the values 2 , 3 , . . . , 12. If we are asked to find P ( X = 3), this is equivalent to finding the probability that the sum of the rolls is 3. We can classify random variables according to the possible values it may take. In this example, the random variable X is a finite random variable, as it can only take on a finite number of values. It is also possible that a random variable may be infinite discrete (if it takes on an infinite list of values) or continuous (if it takes on...
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 Spring '11
 stephenlang
 Calculus

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