To find the mean of a data set, you need to sum up all the values and divide the sum by the number of values in the data set.
Let's calculate the mean for the given data set:
Sum of the values: 8 + 5 + 15 + 12 + 10 = 50
Number of values: 5
Mean = Sum of values / Number of values
Mean = 50 / 5
Mean = 10
Therefore, the mean of the given data set is 10.