Don't know if you're still reading this thread, but one thing I'm stumped on is that if I plug in 8.333 instead of 9, I get a probability of around 65%.

If I plug in 7, I still get a probability of above 50%, which seems to conflict with the 8.333 answer calculated upstream.

Wouldn't a positive EV imply that a 50% probability is the break-even?