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P(X=x)={2kif x=0kxif x=1k(x−1)if x=2 or 30otherwiseP(X = x) = \begin{cases} 2k & \text{if } x = 0 \\ kx & \text{if } x = 1 \\ k(x - 1) & \text{if } x = 2 \text{ or } 3 \\ 0 & \text{otherwise} \end{cases}

The value of k is

Solution

✅ Correct Option: 2

We know that xx can only take values 0,1,2,30, 1, 2, 3 since P(X=x)=0P(X = x) = 0 for everything else.

P(X=0)=2kP(X = 0) = 2k

P(X=1)=k(1)=kP(X = 1) = k(1) = k

P(X=2)=k(2−1)=kP(X = 2) = k(2 - 1) = k

P(X=3)=k(3−1)=2kP(X = 3) = k(3 - 1) = 2k


For any probability distribution, the sum of all probabilities must always equal 11 (since one of the outcomes has to happen).

P(X=0)+P(X=1)+P(X=2)+P(X=3)=1P(X=0) + P(X=1) + P(X=2) + P(X=3) = 1

2k+k+k+2k=12k + k + k + 2k = 1

6k=16k = 1


k=16k = \dfrac{1}{6}

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