At the conclusion of the hearing, if the board of supervisors approves the resolution or petition as originally presented or in modified form, it shall by resolution entered upon its minutes:
(a) Fix and describe the exterior boundaries of the proposed district as determined by the board of supervisors.
(b) Fix the date on which an election will be held in the proposed district and the hours during which the polls will be open.
(c) State the purpose for which the election is held.