Thanks..I really found this explaination very useful.If nothing else you can always apply brute force.
List the first 10 numbers of Fibonacci sequence. (I assume you can do this)
Find their mean.
For each number in the sequence find the absolute value of the difference between it and the mean.
Sum the absolute differences found above and divide by 10.
Since the Fibonacci sequence has structure it may be possible to come up with a cleverer formula for this but you'll probably spend more time deriving it than just brute forcing on such a small data set.