There are 3 fictions and 6 non-fictions. How many cases are there such that 2 fictions and 2 non-fictions are selected from them?\nOptions:\n(A) 90\n(B) 120\n(C) 45\n(D) 180\n(E) 200 OK. Let's think. Some random thoughts first:
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Number of ways of selecting 2 fiction books = 3C2\nNumber of ways of selecting 2 non fiction books = 6C2\n3C2 * 6C2 = 3 * 15 = 45 The answer: (C).
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