[DownUnder]

Villain was a poster who checked, so could have anything.

On the turn, you have 6 outs to beat A2 and A5, 8 outs to beat 52 and you're drawing dead against 22, 55 and 34. We can probably ignore the possibility of him holding the last two Aces.

There are 16 combinations of 34, 3 ways for 22 and 3 ways for 55 - that's 22 ways you're drawing dead.

There are 6 ways each for A5 and A2 and 9 ways for 52, so 21 ways you have outs (more if there are any other holdings villain would cap the flop with - unlikely, but you never know I guess).

So it looks like you're drawing dead half of the time and have 6-8 outs the other half - that's an average of 3-4 outs. Getting 11.5-1 on the turn makes the call pretty marginal.

DU