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Math help

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hurrisun
Posts: 6284 - Karma: 49
I wouldt usually do this but i have a test tomorrow and need help this is grade 12 data management

so the question is how many permutations are there of the letters in the word baseball?

so the anwser to that is

8!
-----
2! 2! 2!

= 40320
________
8

which equals 4200 permutations of the word baseball

now that took all of my cunning and i was pretty hapy wen i got it then i look down to part B and it says

How many of these permutations start with the letter A and my mind imploded

please help me :D
Oct 3 2007 4:43PM
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hurrisun
Posts: 6284 - Karma: 49
the anwser is not 4200 its 5040 my mistake
Oct 3 2007 4:45PM
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hurrisun
Posts: 6284 - Karma: 49
i messed up up there pretty much ignnore that and anwser this of the 5040 permutations of the word baseball how many of them stat with the letter A a permutation is an arrangement of the letters and the anwser to how many start with A is 1260 i jsut dont no how to arrive to that
Oct 3 2007 4:46PM
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Itsbackfliptime
Posts: 18901 - Karma: 75
just figure out how many permutations there are in a 7 letter word. Since you know the a is going to be at the beginning then you can just figure out the.
You do n! / (n-r)! so in this case n would be 7 and r would be 7. So your answer will be 7!.
Oct 3 2007 4:49PM
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hurrisun
Posts: 6284 - Karma: 49
no cuz 7!=5040
Oct 3 2007 4:52PM
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hurrisun
Posts: 6284 - Karma: 49
there are 3 repeating letters so u gotta think about those i think

cuz there are 2 A's 2 l's and 2 b's and if you divide the total anwser by 3 you get the proper anwser i dont really pay attention in math class but the equation the teacher uses is alot more complicated for that and i need work marks
Oct 3 2007 4:55PM
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jimmychung
Posts: 6857 - Karma: 25
you have to limit the first letter in the sequence to just A, so there can be only 1 possibility there. that's as far as i can take you from there for now, i'm beat.
Oct 3 2007 4:58PM
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hurrisun
Posts: 6284 - Karma: 49
no there are 2 possibilities for the first letter since there are 2 a's
Oct 3 2007 5:01PM
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Itsbackfliptime
Posts: 18901 - Karma: 75
so multiply it by 2. It doesn't matter if characters are repeated. Heres an applet that does it for you.

http://www.digsys.se/js_permut.html?inputdata=aba&outputdata=abcd%0D%0Aabdc%0D%0Aacbd%0D%0Aacdb%0D%0Aadcb%0D%0Aadbc%0D%0Abacd%0D%0Abadc%0D%0Abcad%0D%0Abcda%0D%0Abdca%0D%0Abdac%0D%0Acbad%0D%0Acbda%0D%0Acabd%0D%0Acadb%0D%0Acdab%0D%0Acdba%0D%0Adbca%0D%0Adbac%0D%0Adcba%0D%0Adcab%0D%0Adacb%0D%0Adabc%0D%0A
Oct 3 2007 5:09PM
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hurrisun
Posts: 6284 - Karma: 49
it does matter and that "applet" cant handle the word baseball it jsut tells me things i already no
Oct 3 2007 5:15PM
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Itsbackfliptime
Posts: 18901 - Karma: 75
do it with a shorter word. It confirms what I said.
Oct 3 2007 6:28PM
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