Use some thinking to answer the following question. The average of nine numbers is 17. The average of first four numbers is 20 and the average of last four numbers is 16. What is the middle number?\nOptions:\n(A) A) 7\n(B) B) 8\n(C) C) 9\n(D) D) 10\n(E) E) 11
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The total of nine numbers = 9X17 = 153\nThe total of first 4 and last 4 numbers is = 4 X 20+4 X 16 = 144\nSo, the middle number is (153 - 144 ) = 9 So the final answer is (C).
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