If X is a Poisson variate such that 3P(X = 2) = 2P(X =1), then P(X = 0) is equal to: (Given e-4/3 = 0.264)
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 0.264
For a Poisson variate with mean λ, \( P(X=r)=\frac{e^{-\lambda}\lambda^r}{r!} \).
\( \displaystyle 3\cdot\frac{e^{-\lambda}\lambda^2}{2}=2\cdot e^{-\lambda}\lambda \)
Dividing by \( e^{-\lambda}\lambda \) (λ > 0):
\( \displaystyle \frac{3\lambda}{2}=2 \)
\( \displaystyle \lambda=\frac{4}{3} \)
\( \displaystyle P(X=0)=e^{-\lambda}=e^{-4/3} \)
\( \displaystyle =0.264 \)