Answer:
Step-by-step explanation:
It is a parameter, I think. The population is limited to all of the restaurant's customers. Presumably they don't come in to look at the waitresses -- although that might happen. They are there for coffee donuts or a meal, so they are spending money, that's what all of them have in common.
So the population is very confined and very well defined.
The owner is finding a mean. Anything like this is a parameter which defines some aspect of the population.
