Q: A parking lot has 2 entrances. Cars arrive at entrance 1 and 2 according to a Poisson distribution an average of 3/hour, and entrance 2 at an average of 4/hour, respectively. What is the probability that a total of 3 cars will arrive at the parking lot in a given hour? (assume arrivals are independent at the 2 entrances).

Solution:

Is this correct?