OMIS 2010 Chapter Notes - Chapter 07: Random Variable, Countable Set, Standard Deviation

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Chapter 7: random variables and discrete probability distributions. This section introduced the concept of a random variable, which assigns a numerical value to each simple event in a sample space, thereby enabling us to work with numerical-valued outcomes. A random variable is discrete if the number of possible values that it can assume is finite or countably infinite; otherwise, the random variable is continuous. The second important concept introduced was that of a discrete probability distribution, which lists all possible values that a discrete random variable can take on, together with the probability that each value will be assumed. When constructing a discrete probabil- ity distribution, bear in mind that the probabilities must sum to 1. The local taxation office claims that 10% of the income tax forms processed this year contain errors. Suppose that two of these forms are selected at random.