Mean is average.
The data set is: (-7), (-10), (-1), 0, (-4), (-7), 3, (-2),1
You find mean by adding up all of the values and dividing them by the number of values.
-7 + -10 + -1 + 0 + -4 + -7 + 3 + -2 + 1 = -27
you divide this by 9 because there are 9 seperate values.
-27/9 = -3
The mean of the data set is -3
Hope I helped!
Let me know if you need anything else!
~ Zoe
