Nah, I bet the odds are significantly greater than that, but it kind of depends on how much effort the newbie puts into the OP of the thread he started.  I think this was mentioned, but it seems like most newbies who create threads don't end up posting in them ever again.  It's almost as if they don't really want to discuss whatever the topic of their thread is; they just want to try their luck at getting merits.  Sometimes it works if the post isn't horrible, but I'd say it's more like a 10-20% chance that they do end up with some merits.

If you define "luck" as the generosity of a merit source that happens to read a thread started by a newcomer, then yeah, I'd agree.  But the main factor is the member's writing skill and the importance/significance of the topic--and we all know most of these threads are just complete crap and should never have been started in the first place.