InterviewSolution
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Find the number of words formed by permuting all the letters of the following words :(i) INDEPENDENCE(ii) INTERMEDIATE(iii) ARRANGE(iv) INDIA(v) PAKISTAN |
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Answer» (i) INDEPENDENCE Here's 12 letters in the word ‘INDEPENDENCE’ out of which 2 are D’s, 3 are N’s, 4 are E’s and the rest all are distinct. Therefore by using the formula, n!/ (p! × q! × r!) The total number of arrangements = 12! / (2! 3! 4!) = [12 × 11 × 10 × 9 × 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1] / (2! 3! 4!) = [12 × 11 × 10 × 9 × 8 × 7 × 6 × 5] / (2 × 1 × 3 × 2 × 1) = 11 × 10 × 9 × 8 × 7 × 6 × 5 = 1663200 (ii) INTERMEDIATE Here's 12 letters in the word ‘INTERMEDIATE’ out of which 2 are I’s, 2 are T’s, 3 are E’s and the rest all are distinct. Therefore by using the formula, n!/ (p! × q! × r!) The total number of arrangements = 12! / (2! 2! 3!) = [12 × 11 × 10 × 9 × 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1] / (2! 2! 3!) = [12 × 11 × 10 × 9 × 8 × 7 × 6 × 5 × 3 × 2 × 1] / (3!) = 12 × 11 × 10 × 9 × 8 × 7 × 6 × 5 = 19958400 (iii) ARRANGE There are 7 letters in the word ‘ARRANGE’ out of which 2 are A’s, 2 are R’s and the rest all are distinct. Therefore by using the formula, n!/ (p! × q! × r!) The total number of arrangements = 7! / (2! 2!) = [7 × 6 × 5 × 4 × 3 × 2 × 1] / (2! 2!) = 7 × 6 × 5 × 3 × 2 × 1 = 1260 (iv) INDIA Here's 5 letters in the word ‘INDIA’ out of which 2 are I’s and the rest all are distinct. Therefore by using the formula, n!/ (p! × q! × r!) The total number of arrangements = 5! / (2!) = [5 × 4 × 3 × 2 × 1] / 2! = 5 × 4 × 3 = 60 (v) PAKISTAN Here's 8 letters in the word ‘PAKISTAN’ out of which 2 are A’s and the rest all are distinct. Therefore by using the formula, n!/ (p! × q! × r!) The total number of arrangements = 8! / (2!) = [8 × 7 × 6 × 5 × 4 × 3 × 2 × 1] / 2! = 8 × 7 × 6 × 5 × 4 × 3 = 20160 |
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