Exhibit 23(b) CONSENT OF ENGINEER We hereby consent to the incorporation by reference in this registration statement of our estimates, dated January 9 and 23, 1996, which appear in the MDU Resources Group, Inc. Annual Report on Form 10-K for the year ended December 31, 1995. RALPH E. DAVIS ASSOCIATES, INC. /s/ Joseph Mustacchia Jr. Executive Vice-President Houston, Texas June 14, 1996