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, 2002 December 31, 2001 (In thousands of dollars) Earnings Available for Fixed Charges: Net Income per Consolidated Statements of Income $ 128,320 $ 155,849 Income Taxes 80,442 98,341 208,762 254,190 Rents (a) 7,687 6,561 Interest (b) 50,230 51,201 Total Earnings Available for Fixed Charges $ 266,679 $ 311,952 Preferred Dividend Requirements $ 759 $ 762 Ratio of Income Before Income Taxes to Net Income 163% 163% Preferred Dividend Factor on Pretax Basis 1,237 1,242 Fixed Charges (c) 57,917 57,762 Combined Fixed Charges and Preferred Stock Dividends $ 59,154 $ 59,004 Ratio of Earnings to Fixed Charges 4.6x 5.4x Ratio of Earnings to Combined Fixed Charges and Preferred Stock Dividends 4.5x 5.3x (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.