The powers of each authority shall be vested in the commissioners in office from time to time. Three commissioners of a 5-member board, 4 commissioners of a 7-member board, and 5 commissioners of a 9-member board, respectively, shall constitute a quorum of the authority for the purpose of conducting its business and exercising its powers and for all other purposes. Action may be taken by the authority upon a vote of a majority of the commissioners present at a meeting at which there is a quorum, unless the bylaws of the authority require a larger number for a particular matter.