The trustees shall elect from among the elected membership a chair, secretary, and other officers as they determine. The trustees shall meet at least four times a year at places and on dates they determine. The chair may call other meetings, and must call one at the request of six or more trustees. The secretary shall notify in writing every trustee of the time and place of every meeting at least seven days in advance of the meeting, except that meetings may be held on shorter notice if all trustees agree. Ten trustees constitute a quorum to conduct business. If at any time there is no director, the chair shall assume the director’s duties and powers. The chair with the consent of the trustees may appoint an advisory council.