Department Store
a Large Department Store Records the Number of Returns

Essay

Department store
A large department store records the number of returns per day in women's dresses for reasons such as wrong size; husband didn't like it,color,etc.The manager of the women's dresses department recalls from her statistics class in college that the Poisson distribution might describe such events.A random sample of 150 days is taken.The number of returns per day in the sample as well as the observed frequencies are shown below: $$\begin{array} { | c | c | } \hline \begin{array} { c } \text { Number of } \\\text { Returns Per Day }\end{array} & \begin{array} { c } \text { Observed } \\\text { Frequency }\end{array} \\\hline 0 & 21 \\1 & 37 \\2 & 44 \\3 & 30 \\4 & 14 \\> 4 & 4 \\\hline\end{array}$$
-She tests the hypothesis that returns per day are Poisson distributed with a population mean equal to 1.90.Her significance level is 0.05.Identify the critical value.