There are 9 jars each with unique labels.
Someone has come and removed all the labels and mixed them up.
If you put the labels back on the jars (without knowing the contents), what is the expected number of labels which would match the contents?
these terms (expected and average) often mean the same thing in these types of problems, but is it *necessarily* so? My brain has convinced me that there is a subtle difference that might be important. The "expected" term used to ask for the guess which would be most likely to be true, and previously I've always thought of this as the average. But...
Wouldn't the most likely outcome be something else? (Im going to guess 0, but thats just a blind guess) Even though the picker will average 1 correct jar doesn't mean he will get one correct more often than any other value. The situation that brought this to mind was the 2 jar pattern shown by f.l. With two jars, youre either 0 or 2 correct - you cannot get the "expected" answer, so why would you expect it?
Semantics...
expected or average
