If an initiated petition, or amended petition as defined in Article VIII, Section 3, be found sufficient by the city secretary, the city secretary shall immediately so certify and promptly submit the ordinance therein set forth to the commission, which shall at once read the proposed ordinance and refer it to an appropriate committee, which may be a committee of the whole. Provisions shall be made for a public hearing upon the proposed ordinance before the committee to which it is referred and notice of such hearing shall be published in the official newspaper one time at least five days before the date fixed for the hearing. Thereafter the committee shall report the ordinance to the commission, with its recommendations thereon, not later than sixty days after the date on which such ordinance was submitted to the commission by the city secretary. Upon receiving the ordinance from the committee, the commission shall proceed at once to consider it and to take final action thereon within thirty days from the date of such committee report.