The Number of Cars Arriving at Joe Kelly's Oil Change

Essay

The number of cars arriving at Joe Kelly's oil change and tune-up place during the last 200 hours of operation is observed to be the following: $$\begin{array}{l}\text { Number of }\\\begin{array} { l c } \text { Cars Arriving } & \text { Frequency } \\\hline 3 \text { or less } & 0 \\4 & 10 \\10 & 30 \\6 & 70 \\7 & 50 \\8 & 40 \\9 \text { or more } & 0\end{array}\end{array}$$
Determine the probability distribution of car arrivals.