Chapter 5 - Discrete Probability Distributions - 5-1 Probability Distributions - Extending the Concepts - Page 264: 33

P(X) =3/6+4/6+7/6 $\gt$ 1 It is not a probability distribution, since the sum of the probabilities of all the events in the sample space is greater than 1, and the probability of one of the event P(X) = 7/6 is not between 0 and 1, it does not fulfill the two requirements for a probability distribution.

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