Answer
$$mean = 3.8$$
$$median = 5$$
$$mode = 5$$
Work Step by Step
To calculate the mean, sum the data values in the set and divide by the number of data values in the set:
$$mean = \frac{-3+4+5+5-2+7+1+8+9}{9}=3.8.$$
The median is the middle value of the data set when it is arranged in increasing or decreasing order:
$$-3,-2, 1, 4, 5, 5, 7, 8, 9.$$
So
$$median = 5.$$
The mode is the value which occurs most often in the data set:
$$mode = 5.$$
