Final answer:
Based on experimental outcomes of the ultimatum game, the most likely payout combination to be accepted by both players would be one that is near an even split, such as $45 for Justine and $30 for Sarah, as it appears relatively fair.
Step-by-step explanation:
In the ultimatum game, Justine (the proposer) has $75 to allocate, and Sarah can accept or reject the offer. Experimental data suggests that players do not behave entirely in self-interest; they often reject offers that deviate significantly from a fair split. It is more likely that an offer close to an even distribution would be accepted even if it is not exactly 50-50.
Additionally, a player's decision may be influenced by the total sum of money involved and by strategic considerations, especially if the game is repeated. As such, the most likely outcome for a one-time game would typically be $45 for Justine and $30 for Sarah or something analogous, as it appears fair enough to both parties involved.