# Averaging with a tolerance

I'm having some issues with trying to average some values. Lets say (for this example) that earthquakes are measured on a scale of 1-6. No earthquake can be stronger than a 6 and you want to calculate on average strength of the earthquakes in one area. For instance you have a single 6 rated earthquake and three 3 rated earthquakes. The way i'm calculating it, i'm getting values that make no sense. I'm weighing the earth quakes by the corresponding values saying that a single earthquake is like a 6 in my average and the three 3's are equivalent to 9 however when you take this average you get 7.5 which obviously makes no sense since no earthquake can be weighted more then a 6??? I know this is vague and i'm probably making no sense but if you do understand the jargon i'm trying to ask, could you please answer. Thank you.

To calculate the mean, you add all the values and divide by the number of them. In your example, the mean is $\frac {6+3+3+3}{4}=\frac{15}4=3.75$, which is well within range. When you count the number, repeated values must be counted over again.