# 8 books

• September 11th, 2014, 04:17 AM
Din0queen
8 books
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.
• September 11th, 2014, 09:30 AM
cosmictraveler
• September 25th, 2014, 01:51 AM
tazammal
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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iqbal
• September 25th, 2014, 02:39 AM
甘肃人
Sheesh! This is why I don't even have maths books. Good luck, brother. I can't stay awake long enough to help you.