$X$ follows a Poisson distribution with $\lambda = 2$. What is $P(X = 1)$? (Take $e^{-2} = 0.1353$.)

Explanation

1. 01

   $P(X = r) = \frac{e^{-\lambda}\lambda^{r}}{r!}$ with $\lambda = 2$, $r = 1$.

2. 02

   $= \frac{0.1353 \times 2^{1}}{1!} = 0.2706$.