We can first find the mean, which is 80/10=8.

Now, for each number: subtract the Mean and square the result!

So, (15-8)^2, (8-8)^2, (14-8)^2, (7-8)^2, (6-8)^2, (8-8)^2, (2-8)^2, (8-8)^2, (9-8)^2, (3-8)^2

Which is, 49, 0, 36, 1, 4, 0, 36, 0, 1, 25

Now, find the mean, which is 49+0+36+1+4+0+36+0+1+25/10=15.2!