A study of the checkout lines at the Safeway Supermarket in the South Strand area revealed that between 2.00pm to 5.00pm on weekdays, there is an average of 18 customers waiting in line.

i. If you visit Safeway between 4.00pm to 4.30pm on one particular weekday, what is the probability that there are not more than three customers waiting?

ii. If the average revenue from each customer is RM25, what is the mean hourly revenue earned by the supermarket for one particular weekday's afternoon.