1, 2, 3, 3, 4, 4, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 11 is your set and you cross each off one by one on each side till you get to the middle. Finding the median is easy here is an example.
1 is crossed off then 11, then 2, then 9, then 3, then 9, and again till you reach the middle. that would be the median. If there is two numbers in the middle, such as 6 in this case, you add them numbers and divide it by 2. So 6+6= 12 and 12 divided by 2 equals 6. So your answer is 6