'Why do we get Queues and Waiting Lists'

[BrianNevin]

I find this really useful and will be using this in an upcoming Demand & Capacity Learning set.
Thanks folks

(There are 2 typos which may be misleading: Page 17, para 4, main demand min: 5, max 13 and Page 28, para 1, capacity min 15, max = 15)