between 2000 Proble Problem 13. and 3000 can be formed with the digits 0, 1, 2, 3, 4, 5, worn in 6, 7? (repetition of digits not allowed) the nun 210 Problem 13.2.11 Using the letters A,B,C,D,E,F,G, how many FOUR letter "words" can we form if: (a) We can repeat a letter? 2401 (b) We cannot repeat a letter? 840 120 (c) The word must begin with an A and we cannot repeat a letter? 240 24 Prob ton de bers natio can 637 (d) The word must begin with an A or end with A and we cannot repeat a letter? Pr chc CO (e) The word must begin with an A or end with A and we can repeat a letter? of 12 mem