How to determine a quorum?
A quorum is set by the legislative or deliberating body in question. It is the minimum number or members who must be present in order to pass a vote. The U.S. Constitution allows that both the House and Senate have a simple majority, with the one exception being the instance of their having to choose the President or Vice President when the electoral college fails to get the majority vote to do so. In this case the quorum is a necessary two-thirds state representation. For more information look here: http://en.wikipedia.