A QT convenience store has a small adjacent parking lot that has ten

parking spaces reserved for the store$$s customers. During store hours, cars enter the lot and

$($try to$)$ use one of the spaces at a mean rate of $20$ per hour. There is another convenience store

down the road, so customers that arrive and find the lot full will go to this other convenience

store. The following table provides Pn for n $=0,1,...,10$ where n is the number of cars in

parking spots at the QT: