11, 2, 24
I tested for Mensa once, and at least one of the tests had sequences, some numeric like this. During one of the questions, it occurred to me that there could be multiple “right” answers, but some of the answers included were “righter” than others.
Then it occurred to me that there could be some questions that did not have ANY right answers; they were put there by the test constructors to see which answers were selected by the more intelligent testees. Then, by comparing what the rest of us answered, our final scores were adjusted based on how we had answered the same questions.
Paranoid much?
Nope. This one is not an arithmetic series. See the spoiler I posted three posts above yours.