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Please explain

by Pedros » Thu Jul 30, 2009 3:58 am
A 4-letter code word consists of letters A, B, and C. If the code includes all the three letters, how many such codes are possible?

A) 72
B) 48
C) 36
D) 24
E) 18

I would appreciate if you can explain your steps to answer this one......
Thanks
answer C
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Re: Please explain

by dtweah » Thu Jul 30, 2009 4:45 am
Pedros wrote:A 4-letter code word consists of letters A, B, and C. If the code includes all the three letters, how many such codes are possible?

A) 72
B) 48
C) 36
D) 24
E) 18

I would appreciate if you can explain your steps to answer this one......
Thanks
answer C
(ABC) x A or B or C

(ABC) A (ABC)B (ABC) C

These are the only choices. They are mutually exclusive. Find the mutuation in each and add. There will be 2 letters repeating in each so you have to divide by 2 factorial.

(4!/2! ) x 3

36

Choose C.
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by Pedros » Thu Jul 30, 2009 6:12 am
Dtweah......... thank you
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