A table records the value 1 three times, the value 4 twice and the value 5 three times. What is the mean of these eight values?

Explication

The eight values total 3 x 1 + 2 x 4 + 3 x 5 = 26, and 26 divided by 8 gives 3.25. Dividing the same total by the 3 different values named gives about 8.67, a figure larger than every value in the data, which no mean can be, so the divisor has to be the number of observations.