At the conclusion of the hearing, the board shall, by resolution, determine whether it is deemed necessary to incur the bonded indebtedness, and, if so, the resolution shall also state the purposes for which the proposed debt is to be incurred, the estimated cost of accomplishing those purposes, the amount of the proposed debt, that the exterior boundaries of the portion or portions of the district which will be benefited are set forth on a map on file with the secretary of the district, which map shall govern for all details as to the extent of the improvement district or districts, and that each portion or portions of the district set forth on the

map shall thereupon constitute and be known as “Improvement District No. ____ of the Southern California Rapid Transit District,” and the determinations made in the resolution shall be final and conclusive.