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#1 2011-02-25 17:05:03
- suhana
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- Registered: 2011-02-25
- Posts: 31
please help meeee... identification number and repetitions
assume that the identification number for all employees in an organization is formed by using two letter from the selection alphabets A, B, C, D, E followed by five digit from the digits 1, 2, 3, 4, 5, 6, 7, 8 and 9. how many employee identification number can be designed,
a) if no repetitions of alphabets an numbers are allowed?
b) if no repetitions of alphabets and numbers are allowed, in addition the first alphabet must be an A the last number must be a 9?
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#2 2011-02-25 17:23:14
- gAr
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- Registered: 2011-01-09
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Re: please help meeee... identification number and repetitions
Hi suhana,
a)
There are 5 ways to choose the first alphabet, and 4 ways to choose the second.(since no repetitions allowed). Therefore, 5*4 ways in total.
There are 9 ways to choose first digit, 8 for the second ... Hence 9*8*7*6*5 for the digits.
Totally, (5*4)*(9*8*7*6*5)
b)
Only one way for the first alphabet, and 4 for the 2nd. = 1*4 ways
1 way for the last digit, hence 8*7*6*5 ways for the digits.
In total (1*4)*(8*7*6*5*1) ways
"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense" - Buddha?
"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."
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#3 2011-02-25 17:29:34
- suhana
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- Registered: 2011-02-25
- Posts: 31
Re: please help meeee... identification number and repetitions
can i know what fomula u use this question...
becouse i'm stress about subjek probability and statistics
thanks for help me..:)
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#4 2011-02-25 17:38:53
- gAr
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- Registered: 2011-01-09
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Re: please help meeee... identification number and repetitions
Well, what I used is permutations.
More important than the formula is to understand it.
Check this: http://www.mathsisfun.com/combinatorics/combinations-permutations.html
Don't get stressed, enjoy it!
"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense" - Buddha?
"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."
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#5 2011-02-25 18:32:54
- suhana
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- Registered: 2011-02-25
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Re: please help meeee... identification number and repetitions
(a) (5*4)*(9*8*7*6*5)
=20*15120
=302,400
(b) (1*4)*(8*7*6*5*1*)
=4*1680
=6,720
correct or not the answers I give?
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#6 2011-02-25 18:52:17
- gAr
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- Registered: 2011-01-09
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Re: please help meeee... identification number and repetitions
Correct!
"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense" - Buddha?
"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."
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#7 2011-02-25 18:55:40
- suhana
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- Registered: 2011-02-25
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Re: please help meeee... identification number and repetitions
gAr
can you help me the question cumulative distribution function?
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#8 2011-02-25 19:02:18
- gAr
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- Registered: 2011-01-09
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Re: please help meeee... identification number and repetitions
Ask the question, I'll tell if I know.
"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense" - Buddha?
"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."
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