Mean (or arithmetic mean) is a type of average. It is computed by adding the values and dividing by the number of values. Average is a synonym for arithmetic mean – which is the value obtained by dividing the sum of a set of quantities by the number of quantities in the set. An example is (3 + 4 + 5) ÷ 3 = 4. The average or mean is 4. Two other common forms of averages are the median and mode. The median is the middle value of the set when they are ordered by rank – or the point in a series of numbers above and below which is half of the series. An example would be: The median income of a four-person family in Connecticut is $82,517. The mode is the most frequent value in a set of data. If you had nine students taking an exam and the scores were: 91, 84, 56, 90, 70, 65, 90, 90, 30 – then the mode is 90, the most common score. The median (middle) score is 84.