Salary payments for supervision of interns may be made out of district funds and may be met by reducing proportionately the salaries paid interns. Under this authorization no more than eight interns may be supervised by one staff member and the normal district salary paid each intern may be reduced by as much as, but no more than, one-eighth to pay the salary of the supervisor. In no event may an intern be paid less than the minimum salary required to be paid by the state to a regularly certificated teacher.