MDU RESOURCES GROUP, INC. COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES AND COMBINED FIXED CHARGES AND PREFERRED STOCK DIVIDENDS Twelve Months Year Ended Ended June 30, 2004 December 31, 2003 (In thousands of dollars) Earnings Available for Fixed Charges: Net Income (a) $180,420 $ 170,956 Income Taxes (b) 90,565 93,751 270,985 264,707 Rents (c) 9,284 9,073 Interest (d) 57,890 54,354 Total Earnings Available for Fixed Charges $338,159 $ 328,134 Preferred Dividend Requirements $ 685 $ 717 Ratio of Income Before Income Taxes to Net Income 147% 153% Preferred Dividend Factor on Pretax Basis 1,007 1,097 Fixed Charges (e) 71,120 68,141 Combined Fixed Charges and Preferred Stock Dividends $ 72,127 $ 69,238 Ratio of Earnings to Fixed Charges 4.8x 4.8x Ratio of Earnings to Combined Fixed Charges and Preferred Stock Dividends 4.7x 4.7x (a) Net income excludes undistributed income for equity investees. (b) Includes income tax benefits of $4,821 associated with the cumulative effect of accounting change for the twelve months ended December 31, 2003. (c) Represents interest portion of rents estimated at 33 1/3%. (d) Represents interest, amortization of debt discount and expense on all indebtedness and amortization of interest capitalized, and excludes amortization of gains or losses on reacquired debt (which, under the Federal Energy Regulatory Commission Uniform System of Accounts, is classified as a reduction of, or increase in, interest expense in the Consolidated Statements of Income) and interest capitalized. (e) Represents rents (as defined above), interest, amortization of debt discount and expense on all indebtedness, and excludes amortization of gains or losses on reacquired debt (which, under the Federal Energy Regulatory Commission Uniform System of Accounts, is classified as a reduction of, or increase in, interest expense in the Consolidated Statements of Income).