so given that the probability of a customer entering a store is between 50 and 70 years old is 5/9. What is the probability that the 7th customer entering the store is also the 3rd customer who is between 50 and 70? Then, with 7 people in the store, what is the probability that 3 of them are between 50 and 70 years old?
I'm having trouble figuring out how to approach these - I thought about setting the two Poisson distributions equal, but that didn't get me anywhere. I'm wondering if it requires a conditional probability.