A probability can be interpreted as the proportion of times that a certain

# A probability can be interpreted as the proportion of

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A probability can be interpreted as the proportion of times that a certain event can be expected to occur. If the probability of an event is more than 1, then it will occur more than 100 % of the time (impossible). 4 PROBABILITY RULE B All possible outcomes together must have probability 1. Because some outcome must occur on every trial, the sum of the probabilities for all possible outcomes must be exactly one. If the sum of all of the probabilities is less than one or greater than one, then the resulting probability model will be incoherent. 5 PROBABILITY RULE C The probability that an event does not occur is 1 minus the probability that the event does occur. As a jury member, you assess the probability that the defendant is guilty to be 0.80. Thus you must also believe the probability the defendant is not guilty is 0 . 20 in order to be coherent (consistent with yourself). If the probability that a flight will be on time is 0.70, then the probability it will be late is 0.30. 6 PROBABILITY RULE D If two events have no outcomes in common, they are said to be mutually exclusive . The probability that one or the other of two mutually exclusive events occurs is the sum of their individual probabilities. 7 PROBABILITY RULE D If two events have no outcomes in common, they are said to be mutually exclusive . The probability that one or the other of two mutually exclusive events occurs is the sum of their individual probabilities. Age of woman at first child birth 7 PROBABILITY RULE D If two events have no outcomes in common, they are said to be mutually exclusive . The probability that one or the other of two mutually exclusive events occurs is the sum of their individual probabilities. Age of woman at first child birth under 20: 25 % 7 PROBABILITY RULE D If two events have no outcomes in common, they are said to be mutually exclusive . The probability that one or the other of two mutually exclusive events occurs is the sum of their individual probabilities. Age of woman at first child birth under 20: 25 % 20-24: 33 % 7 PROBABILITY RULE D If two events have no outcomes in common, they are said to be mutually exclusive . The probability that one or the other of two mutually exclusive events occurs is the sum of their individual probabilities. Age of woman at first child birth under 20: 25 % 20-24: 33 % 25+: ? 7 PROBABILITY RULE D If two events have no outcomes in common, they are said to be mutually exclusive . The probability that one or the other of two mutually exclusive events occurs is the sum of their individual probabilities. Age of woman at first child birth under 20: 25 % 20-24: 33 % 25+: ? Probability a woman is less than 25 when she has her first child?  #### You've reached the end of your free preview.

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