https://math.stackexchange.com/q/401600/8671
It's essentially a basic actuarial science question. Most of the tags don't fit. I'd say actuarial science and probability fit but the other three don't. I'm guessing it was migrated because the people didn't understand what it was talking about. But, everything it was talking about is standard actuarial science knowledge. In fact, it's standard terminology on exams MLC and C in the Society of Actuaries, both of which are preliminary exams.
So, are questions like this not allowed here? Or, did the migraters not understand what it was talking about?