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Thread: 8 books

  1. #1 8 books 
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    please help me, cause I don't know how to do it.
    so say you have 8 books of which 5 are English and 3 are Spanish
    if you put them in any order, there are 8! (=40320) ways to do it.
    if you have to put the English books together and the Spanish ones random, there are 3 Spanish books so you have 4 places where you can put the bundle of English books, so there are then 5!*3!*4 (=2880) to place the books
    but if the English books have to be put together and the Spanish ones as well, how do you do it?
    I thought it would just be 5!*3! but my maths book says you have to use the rule of #(A∪B)= #(A) + #(B) - #(A∩B) and I don't get it anymore.


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  3. #2  
    Forum Radioactive Isotope cosmictraveler's Avatar
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  4. #3  
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    if you have to put the English books together and the Spanish ones random, there are 3 Spanish books so you have 4 places where you can put the bundle of English books, so there are then 5!*3!*4 (=2880) to place the books
    but if the English books have to be put together and the Spanish ones as well, how do you do it?









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  5. #4  
    flattened rat 甘肃人's Avatar
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    Sheesh! This is why I don't even have maths books. Good luck, brother. I can't stay awake long enough to help you.
    And what does the Lord require of you but to love justice, to be merciful and to walk humbly with Him?
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