Answer:
11
Explanation:
1. Arrange the numbers from least to greatest.
3,6,8,11,11, 12,13,15, 20
2. Start from the two ends and cross them off until you're left with what's in the middle.
6,8,11,11,12,13,15
8,11,11,12,13
11,11,12
11
3. The median is 11 because that is the number you are left with.