Section 472-I. Quorum to do business

Five members of the board shall be a
  quorum  provided  however  in  the  case where the then current board of
  directors is more than fifteen members then six  members  of  the  board
  shall  be  a  quorum,  and the board may delegate its powers, during the
  interval between its meetings, to an  executive  committee  of  its  own
  members,  whose  minutes  shall  be kept as provided by the by-laws, and
  shall be reported for approval to all stated meetings of the board;  but
  no  purchase  or  conveyance  of real estate shall be made unless by the
  concurrence of a majority of the whole board.