JEE Math Practice Question
If the probability that the random variable $X$ takes the value $x$ is given by $P(X=x)=k(x+1) 3^{-x}, x=0,1,2,3 \ldots$, where $k$ is a constant, then $P(X \geq 3)$ is equal to
- A.$\frac{1}{9}$
- B.$\frac{8}{27}$
- C.$\frac{7}{27}$
- D.$\frac{4}{9}$
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