A mean is an average of a total. If you add all the pets together and divide by the number of people, you get the mean. So 1 +3 + 2 + 4 + 0 = 10
You have 10 pets in total.
There are 5 people.
Mean = 10 pets / 5 people = 2 pets per person. that's the mean or average that everyone has.
