Answer:
He left out a number when putting the numbers in order.
Step-by-step explanation:
To find the median of a set of numbers, first arrange the numbers in order from least to greatest. Then begin crossing numbers of from each side at the same time.
Luke did not cross numbers off from each side, but only crossed them off from the left side. He also skipped a number, given there are only 2 "X's."
The list should look like so:
7, 11, 12, 16, 22, 24, 30
There should be three numbers before 16, not two as he has listed.