Answer: - 1.3
Step-by-step explanation: I believe that it's -1.3 if you're referring to the arithmetic mean. 
(1) Take the sum of -9, -5, -4, -4, -2, 0, 1, 2, 3, 5 and simplify it to -13 
(2) Count the number of terms in the data set. 
{-9, -5, -4, -4, -2, 0, 1, 2, 3, 5}
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10} - The number of terms in the data set is <u>10.</u>  
(3) Divide the sum by the number of terms and simplify. 
-13 / 10 = -1.3 (simplified)