Answer
17
Work Step by Step
We are given the sequence $3, 9, 7, 13, 11...$
Starting at 3, the pattern of this sequence is to add 6 to get the next number and then subtract 2 to get the following number. Then, the pattern repeats. For example, $3+6-2=7$ and $7+6-2=11$.
Therefore, the next number in this sequence is $11+6=17$.
