MDU RESOURCES GROUP, INC. COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES AND COMBINED FIXED CHARGES AND PREFERRED STOCK DIVIDENDS Years Ended December 31, 2001 2000 1999 1998 1997 (In thousands of dollars) Earnings Available for Fixed Charges: Net Income per Consolidated Statements of Income $155,849 $111,028 $ 84,080 $ 34,107 $ 54,617 Income Taxes 98,341 69,650 49,310 17,485 30,743 254,190 180,678 133,390 51,592 85,360 Rents (a) 6,561 3,952 2,018 1,749 1,249 Interest (b) 51,201 51,801 36,539 31,587 33,047 Total Earnings Available for Fixed Charges $311,952 $236,431 $171,947 $ 84,928 $119,656 Preferred Dividend Requirements $ 762 $ 766 $ 772 $ 777 $ 782 Ratio of Income Before Income Taxes to Net Income 163% 163% 159% 151% 156% Preferred Dividend Factor on Pretax Basis 1,242 1,249 1,227 1,173 1,220 Fixed Charges (c) 57,762 55,753 38,557 33,336 34,296 Combined Fixed Charges and Preferred Stock Dividends $ 59,004 $ 57,002 $ 39,784 $ 34,509 $ 35,516 Ratio of Earnings to Fixed Charges 5.4x 4.2x 4.5x 2.5x 3.5x Ratio of Earnings to Combined Fixed Charges and Preferred Stock Dividends 5.3x 4.1x 4.3x 2.5x 3.4x (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.