If, upon the hearing the board determines that it is in the best interests of the district that the lands mentioned in the petition or resolution, or some portion of them, be excluded from the district, or if it appears that the lands, or some portion of them, will not be benefited by their continued inclusion in the district, the board shall make an order that the lands, or some portion of them, as the board may determine, be excluded from the district, describing specifically the lands excluded.