Q.In a take-away food joint with single service counter, the customers are served on a first- come-first-serve basis. The arrival rate of customers follows Poisson distribution, while the expected service time follows exponential distribution. If 2 customers arrive every 10 minutes and 18 customers are served per hour, what is the probability for an incoming customer to wait for more than 30 minutes before being served?
Correct answer: (2/3)e–3