The meetings of the Board of Adjustment shall be held at the call of the chair and at such other times as the Board may determine. Such chair, or in his or her absence the acting chair, may administer oaths and compel the attendance of witnesses. All meetings of the Board shall be open to the public. The Board shall keep minutes of its proceedings, showing the vote of each member on each question, or if absent or failing to vote, indicating that fact, and shall keep records of its examinations and other official actions, all of which shall be immediately filed in the office of the Board and shall be a public record. The presence of four members shall be necessary to constitute a quorum.