11, 12, 13, 10, 15, 8, -------------------, 6
17
6
18
19
16
11, 12, 13, 10, 15, 8, -------------------, 6
It is the combination of two series at alternate positions. First series follows the pattern of +2
and second series follows the pattern of -2. Like 11+2=13, 13+2=15 and so on. Second series
is 12-2=10, 10-2=8 and so on.
So, at the end, 15+2=17