The Phillies were accused of cheating their beer customers by not putting enough beer in their 12 oz. cups. When 15 cups were selected at random, they were found to have mean of
Part of your problem is missing. Perhaps you can post it again.
To find the mean, we need to know the values of the cups. You mentioned that there were 15 cups selected at random, but you didn't provide the values or amounts of beer in each cup.
If you can provide the values of the cups or the amounts of beer in each cup, I can help you calculate the mean.