6 People arrive at a checkout in a store at random, and at a constant mean rate of 0.7 per minute. Find the probability that
- exactly 3 people arrive at the checkout during a 5 -minute period,
- at least 30 people arrive at the checkout during a 1-hour period.
People arrive independently at another checkout in the store at random, and at a constant mean rate of 0.5 per minute.
- Find the probability that a total of more than 3 people arrive at this pair of checkouts during a 2-minute period.