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Question
Let the p. m. f. of a random variable X be __
P(x) = `(3-x)/10` for x = -1,0,1,2
= 0 otherwise
Then E(X ) is ________.
Options
1
2
0
-1
Solution
0
| x | -1 | 0 | 1 | 2 |
| P(x) | `4/10` | `3/10` | `2/10` | `1/10` |
| x.P(x) | `(-4)/10` | 0 | `2/10` | `2/10` |
`sum x.P(x) = 0`
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