Thelma counted the number of apples on each of the apple trees in her backyard. She found
34
3434 apples on her Cortland apple tree,
29
2929 apples on her Red Delicious apple tree,
39
3939 apples on her Empire apple tree, and
34
3434 apples on her Fuji apple tree.
Find the mean absolute deviation (MAD) of the data set
