JEE Math Practice Question
If the probability that the random variable $$\mathrm{X}$$ takes values $$x$$ is given by $$\mathrm{P}(\mathrm{X}=x)=\mathrm{k}(x+1) 3^{-x}, x=0,1,2,3, \ldots$$, where $$\mathrm{k}$$ is a constant, then $$\mathrm{P}(\mathrm{X} \geq 2)$$ is equal to :
- A.$$\frac{7}{18}$$
- B.$$\frac{20}{27}$$
- C.$$\frac{7}{27}$$
- D.$$\frac{11}{18}$$
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