you add 3 then subtract7
n + 20 - 17 + 13 - n = 20 - 17 + 13 = 3 + 13 = 16
13
10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20
Median = 15
The median of {10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20] is the 6th values which is 15.
11- undecagon 12- dodecagon 13- 13-gon 14- 14-gon 15- 15-gon 16- 16-gon 17- 17-gon 18- 18-gon 19- 19-gon 20- 20-gon
5
13
18-the correct number should be 20.
(10 + 13 - 7 + 5 - 2 + 8 - 16 + 4 + 20 - 1)/2
10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20
16.5 is the median.