The board of trustees shall exercise the powers of the authority except where a power has been given to the executive committee by law or by delegation of authority by the board of trustees. A majority of the aggregate number of the members of the executive committee plus the elected members of the board who are not then serving on the executive committee shall constitute a quorum for the purpose of conducting business. All actions may be taken by a vote of a majority of trustees present unless the bylaws require a larger number.