The average of a dataset is given by
Average=Sum of all observationsTotal number of observations.
Consider the dataset 20, 30, 40, 70.
Average=20+30+40+704=1604=40
Consider the dataset 6, 3, 7, 8, 4, 2.
Average=6+3+7+8+4+26=306=5
For the dataset 17, 19, 41, 23, we have
Average=17+19+41+234=1004=25.
Lastly, for the dataset 5, 9, 7, 7, 3, 5,
Average=5+9+7+7+3+56=366=6.