Question

An operations analyst counted the number of arrivals per minute at an ATM in each of 30 randomly chosen minutes. The results were: 0, 3, 3, 2, 1, 0, 1, 0, 0, 1, 1, 1, 2, 1, 0, 1, 0, 1, 2, 1, 1, 2, 1, 0, 1, 2, 0, 1, 0, 1. For the Poisson goodness-of-fit test, what is the expected frequency of the data value X

Answer 1

Step-by-step explanation:

since Poisson distribution parameter is not given so we have to estimate it from the sample data. The average number of of arrivals per minute at an ATM is

$\hat{\lambda}=\bar{x}=\frac{\sum x}{n}=\frac{30}{30}=1$

So probabaility for $\mathrm{X}=1$ is

$P(X=1)=\frac{e^{-\lambda} \lambda^{x}}{x !}=\frac{e^{-1} \cdot 1^{1}}{1 !}=0.3679$

So expected frequency for $X=1$ is $0.3679^{*} 30=11.037$ (or $\left.11.04\right)$ .