Correct me if im wrong but i think to call down in this situation you would be 7.5 to 2 if you consider it to be a decision of either calling to the river or folding on the turn after the check-raise. If that is the question that Card Sharp Cook is asking then he is treating the turn just as the river and it is a question of whether he thinks he is beat or not. If he is more than 78% (7.5/9.5) sure he is beat it is my opinion that he should fold, especially being that he does not have a solid read on the CO.