Answer:
10
Explanation:
It is much easier to do this for one die. There is a 1/6 chance that a 3 occurs on a six-sided die. Another way to say that is that the expected number of 3’s that occur on a roll of a six sided die is 1/6. If we let X be 1 if a 3 occurs on the roll and 0.
Now, if the die is rolled 60 times, then we have 60 different values X1, X2,…,X60
Of course, this shouldn’t be all that surprising. After all, we threw the die 60 times, and there are 6 faces, so it seems reasonable that for a fair die, each face should come up about 10 times.