If a discrete random variable X has the following probability distribution:
X:
P(X): c c2 2c2 c
Then, c = ____________.
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Solution
For a discrete random variable,
Since sum of probability is 1
∴ c + c2 + 2c2 + c = 1
i.e. 3c2 + 2c = 1
i.e. 3c2 + 2c − 1 = 0
i.e. 3c2 + 3c − c − 1 = 0
i.e. 3c (c + 1) − 1 (c + 1) = 0
i.e. c = (∵ c ≠ −1)