Answer:
They went over their goal for the last six months by 34 minutes per month.
Step-by-step explanation:
Mean of a data-set:
The mean of a data-set is the sum of all values in the data-set divided by the size of the data-set.
529, 499, 651, 652, 1,163, and 310 minutes on their cell phone plan.
The mean is:
By how many minutes did they go over their goal in the last six months?
The mean was of 634 minutes, and they wanted to keep it below 600. So
634 - 600 = 34
They went over their goal for the last six months by 34 minutes per month.