Median of the given data is :

-1, 12, 19, -5, -5, -7, 18, 11, -8, 21.

5

Arrange in as Ascending order = -8, -7, -5, -5, -1, 11, 12, 18, 19, 21

N = 10 which is even

Hence, median = \(\frac{(\frac{n}{2})th\;term\;+\;(\frac{n}{2} +1)th\;term}{2}\) 

                      = \(\frac{5th\;term\;+\;6th\;term}{2}\) 

                      = \(\frac{-1\;+\;11}{2}\)  = 5