When all of the members of the board of appraisement cannot agree as to the fair market value of the parcel, the determination of value shall be made in the following manner:
(a) If two of the members of the board agree as to the fair market value, the amount so agreed upon shall constitute the board’s appraisal.
(b) If no two members of the board agree as to the fair market value, then each member of the board shall make a separate appraisal and the average of the three appraisals shall constitute the board’s appraisal.