The numbers need to be arranged in ascending order: {0, 2, 4, 6, 8, 10, 10, 10, 12, 15, 15, 15, 18, 18, 20, 20, 40, 50, 70}
There are 19 numbers in the list, so the middle number (or numbers if there is an even number of data) will be the median.
In this case, the median is the 10th number in the list, which is 12.
Therefore, the median number of hours spent outside for the kids surveyed was 12 hours.