Your late Kevin. Its already been answered. To make it easy for ya, think of what would have occurred had the north not won the 3/5ths compromise, and the South had won the right to count slaves as fully representative populations.
You see it?
:there is actually a little more to the drama, involving the 'tipping' of numbers of seats and gaining a majority to be able to 'veto' etc, but thats a little tedious for here.