A majority of the commissioners shall constitute a quorum for the transaction of any business, for the performance of any duty, or for the exercise of any power of the commission. Any investigation, inquiry, or hearing which the commission has power to undertake or to hold may be undertaken or held by or before any commissioner or commissioners designated for the purpose by the commission. The evidence in any investigation, inquiry, or hearing may be taken by the commissioner or commissioners to whom the investigation, inquiry, or hearing has been assigned or, in his or her or their behalf, by an examiner designated for that purpose. Every finding, opinion, and order made by the commissioner or commissioners so designated, pursuant to the investigation, inquiry, or hearing, when approved or confirmed by the commission and ordered filed in its office, shall be deemed to be the finding, opinion, and order of the commission.