Find the median of the data:   11, 11, 31, 34, 26, 9, 56, 64, 2, 1

18.5

Given data: 11, 11, 31, 34, 26, 9, 56, 64, 2, 1

Now, arrange the data in ascending order, we get:

 1, 2, 9, 11, 11, , 26, 31, 34, 56, 64

Here, the number of observations is 10, which is even

Thus, median = \(\frac{ 5th + 6th }{2}\)

Median = \(\frac{ 11 + 26 }{2}\)

Median = 18.5.