Jane is running a tiny restaurant serving hot-pot buffets. Customers help themselves cook the food in the boiling pot and eat as much as they can within 90 minutes. The timer starts when a (group of) customer gets a table and customers never leave early. Customers will leave right after their arrivals if they find or expect that they cannot get a table in 60 minutes. Suppose customers can accurately expect their waiting time. There are now four tables. Jane wants to use Monte Carlo simulation to compare the current situation with a hypothetical situation wherein there are five tables. She has used historical data to generate random customer arrivals for one night from 6 p.m. to 10 p.m. as listed below.

Index/Time	Index/Time	Index/Time	Index/Time
1 / 06:00	6 / 06:37	11 / 08:12	16 / 08:59
2 / 06:05	7 / 06:58	12 / 08:21	17 / 09:06
3 / 06:08	8 / 07:22	13 / 08:33	18 / 09:18
4 / 06:19	9 / 07:41	14 / 08:39	19 / 09:27
5 / 06:25	10 / 07:55	15 / 08:50	20 / 09:45

(a) Write how you use the simulated arrivals (in the table above) to compute the average waiting time for customer who choose to stay, considering one night with 4 tables.

(b) Write how you use the simulated arrivals (in the table above) to compute the average waiting time for customer who choose to stay, considering one night with 5 tables.