- #1

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## Homework Statement

How many 4-letter codes can be formed using the letters A, B, C, D, E, and F? No letter can be used more than once.

## Homework Equations

N/A?

## The Attempt at a Solution

I really didnt know where to begin . . .

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- Thread starter wvcaudill2
- Start date

- #1

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How many 4-letter codes can be formed using the letters A, B, C, D, E, and F? No letter can be used more than once.

N/A?

I really didnt know where to begin . . .

- #2

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- #3

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If this is assigned from a textbook, then the answer is there. The hint is that it is not combinations, that term is not the math term for it.

- #4

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This problem came from a review worksheet. If this is not a combinations problem, then what is it?

- #5

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- #6

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This implies that after each time I have chosen a letter, there is one less to choose from.

I tried to use n! to find an answer by doing 6x5x4x3x2x1, but the resulting answer was way to large.

- #7

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- #8

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I would think the order is important, but how does that help me?

- #9

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Well, check your textbook. What are you dealing with when order is important?

- #10

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Well, check your textbook. What are you dealing with when order is important?

I dont have a textbook, but im thinking permutations. I dont really know how they differ functionally from a combination though.

- #11

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- #12

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Ok, so I should use n!/(n-r)!

so, 6!/(6-4)! = 360?

so, 6!/(6-4)! = 360?

- #13

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The formula you want is one that is used for combinations, i THINK. You want 6 choose 4 or in other words, how many ways can you choose 4 from 6. The formula for n choose r is [tex]\frac{n!}{(n-r)!r!} \Rightarrow \frac{6!}{(6-4)!4!}[/tex]

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- #14

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The formula you want is one that is used for combinations, i THINK. You want 6 choose 4 or in other words, how many ways can you choose 4 from 6. The formula for n choose r is [tex]\frac{n!}{(n-r)!r!} \Rightarrow \frac{6!}{(6-4)!4!}[/tex]

Originally, I had thought this too, however, I think the order matters here, so the permutation formula must be used.

- #15

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ok sorry. I might do [tex]6 \times 5 \times 4 \times 3[/tex]

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