# Poisson distribution using Chebyshey's inequality

Let $X$ have a Poisson distribution with $\mu = 100$. Use Chebyshev's inequality to determine a lower bound for $\Bbb{P}(75 < X < 125)$.

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$P(|X-100|<2.5(10))=>1-1/2.5^2=0.84$
The variance is $10$? –  Dilip Sarwate Nov 7 '12 at 15:26