Answer:
The mean number of cups of coffer per person was 3.2 cups.
There is nothing in the problem that leads me to believe that the surveys were biased (Was there more to this problem?).
Therefore, we will use all of the values to find the mean. Add up all the values and we have a total sum of 48. Now, divide by 15 to get a mean on 3.2.
Explanation: