Now arranging the runs in ascending order
6, 8, 10, 10, 15, 15, 15, 50, 80, 100, 120
Here 15 occurs more times
∴ Mode = 15
Number of observations (N) is odd
N = 11
Median = (n+1)/2 term
= (11+1)/2
= 12/2 = 6th term
= 15.
So mean, median and mode are equal.