How to Student Not Set It

When we got to the three fifths compromise, one of my students if you years ago said,. why wasn't it three fourths or two thirds or seven eighths or whatever. And I said, no one has ever asked me that question before. And I have no idea but it's a great question. And so I went searching and the best I could find was that it was a ratio that had been discussed in some completely different topic years before - back in England. Like there's no good reason for it. But I never would have even thought to question that how to student not set it...I will never forget that.