Elementary Statistics (12th Edition)

a) The mean: $\frac{18}{30}=0.6.$ b)$P(X=0)=\frac{0.6^0\cdot e^{-0.6}}{0!}=0.5488.$ c) Expected number:$30\cdot 0.5488=16.46.$ d)The expected number is quite close to the actual number.