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 March 31, 2001 December 31, 2000 (In thousands of dollars) Earnings Available for Fixed Charges: Net Income per Consolidated Statements of Income $ 130,351 $ 111,028 Income Taxes 82,975 69,650 213,326 180,678 Rents (a) 4,498 3,952 Interest (b) 54,521 51,801 Total Earnings Available for Fixed Charges $ 272,345 $ 236,431 Preferred Dividend Requirements $ 766 $ 766 Ratio of Income Before Income Taxes to Net Income 164% 163% Preferred Dividend Factor on Pretax Basis 1,256 1,249 Fixed Charges (c) 59,019 55,753 Combined Fixed Charges and Preferred Stock Dividends $ 60,275 $ 57,002 Ratio of Earnings to Fixed Charges 4.6x 4.2x Ratio of Earnings to Combined Fixed Charges and Preferred Stock Dividends 4.5x 4.1x (a) Represents portion (33 1/3%) of rents which is estimated to approximately constitute the return to the lessors on their investment in leased premises. (b) Represents interest and amortization of debt discount and expense on all indebtedness and excludes amortization of gains or losses on reacquired debt which, under the Uniform System of Accounts, is classified as a reduction of, or increase in, interest expense in the Consolidated Statements of Income. (c) Represents rents and interest, both as defined above.