Answer:
I Expect 6.4167 persons arriving during a 55.minute period.
Step-by-step explanation:
If the mean in one hour (60 minutes) is 7, then in a 55 minute period you can expect, by using a rule of three, 7*55/60 = 6.4167 persons. This is because the amount of expected people is always proportional to the amount of time spent waiting for poisson distributions.