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4 different mathematic books and 5 different science books are to be arrange on the shelf.How many possible arrangement can be made if: a. The books on the same subjects are to be arrange together? B. The books are to be arrange alternately?

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thaovtp1407

Answer:

Step-by-step explanation:

Note that arrangements are permutations

  • (a) 4! * 5! * 2! = 24 * 120 * 2 = 5760 possible arrangements

consider the math books and science books as two distinct entities, then you have 2! ways to arrange those two entities

  • (b) arrange the science books first, we have ; 5 m 4 m 3 m 2 m 1

next arrange the math books  5 4 4 3 3 2 2 1 1 = 2880 possible arrangements

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