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Question
State if the following is not the probability mass function of a random variable. Give reasons for your answer.
| X | 0 | -1 | -2 |
| P(X) | 0.3 | 0.4 | 0.3 |
Solution
P.m.f. of random variable should satisfy the following conditions :
(a) 0 ≤ pi ≤ 1
(b) ∑pi = 1.
| X | 0 | -1 | -2 |
| P(X) | 0.3 | 0.4 | 0.3 |
(a) Here 0 ≤ pi ≤ 1
(b) ∑pi = 0.3 + 0.4 + 0.3 = 1
Hence, P(X) can be regarded as p.m.f. of the random variable X.
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