The median is the number in the middle of the data set.
There are 7 numbers, so the 4th number is the median.
(Another method is to eliminate a number on each side until you get to the middle number)
The median is 16.
I hope this helps :)
Answer: 16
Put the numbers in order
12, 15, 15, 16, 19, 21, 25
Put your left pointer finger on 12 and your right pointer finger on 25. Move your left pointer finger to the right and your right pointer finger to the left. The middle number should be 16.
Therefore 16 is the median.