Use Chebyshev's theorem to approximate a probability So I'm having this question in probability and statistics that states the following:
We have an array of Independent random variables Xn, n>0, with a Poisson Distribution P(4), approximate the probability of $\sum_{i=1}^{36}Xi > 120$.
I think I'm supposed to use Chebyshev's theorem but I don't know how to apply it to solve the problem.
Any ideas? 

For a non-negative random variable $Y\geq 0$ we can use Markov's inequality to write
$$
P(Y>a)\leq \frac{EY}{a}.
$$
In your case $Y=\sum_{i=1}^{36}X_i\sim \text{Poi}(4\times 36)$ and $a=120$.
