Twenty-five percent or more of the qualified electors of a city, as shown by the number of votes cast for the executive officer of the city at the preceding city election, may petition for the city manager plan of government. Within thirty days after such petition is filed with the city auditor, the governing body of the city shall provide for the submission of such proposal to the qualified electors of the city at an election to be held within ninety days after such filing. The city auditor shall give thirty days’ notice of the date of the election and of the purposes thereof. The notice of election shall state briefly the powers of the city manager if the plan should be adopted. The election shall be held, the votes canvassed, and the results declared in the same manner as in the case of city elections.