To gamble or not to gamble-New role selection chests

So I have been getting quite lucky for the number of games I've been playing and already have around 140 gold coins. I am wondering if anyone knows the probability for the 80 gold chest to give me the role selection chest(I can't find it anywhere).

If anyone knows what the chances are please tell me. Otherwise I think we all should just go for the guaranteed 240 gold chest