Answer:
66
Step-by-step explanation:
this is actually an almost trick question because it wants to confuse you!
Here's the trick
to work out a mean (average) you add all the components together then divide by the amount of groups.
but here they didn't give you components just the mean of the classes...both of them.
the question says "The mean fpor class A is 66, the mean score for BOTH classes is 66"
so this means that Class B's mean score is 66 too
hope this helps