The petition may be heard without formal pleadings being filed in answer or reply thereto. The election board with whom the petition is filed shall have the authority to issue subpoenas and compel the attendance of witnesses and the production of evidence. Such election board shall have the authority to receive the testimony of witnesses under oath, said oath to be administered by the secretary of the board. At the conclusion of the hearing, the board shall render its decision and the vote of the individual members in writing. The decision of such board shall in all cases be final.