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# simple probability question Watch

1. Was wondering, is there a quick way to work out the total number of arrangements that a given set of letters can make between themselves?

e.g. I know that if I'm given three letters: ABC, there are in total, 6 different ways of arranging them
2. In position 1 there are three letter that can go there (A, B or C). In position 2 two letters can go there (the ones that weren't in pos1). In position 3 only 1 letter is left.
3 x 2 x 1 = 6
3. (Original post by W.H.T)
Was wondering, is there a quick way to work out the total number of arrangements that a given set of letters can make between themselves?

e.g. I know that if I'm given three letters: ABC, there are in total, 6 different ways of arranging them
3! (aka 3x2x1) will give you the answer

for more complicated stuff you'll need to learn this formula: n!/r!(n-r)! (or nCr on your calculator)

n = number of trials (3 in this case)
r is also 3 in this case (i know what values to use for this but i never know what it generally represents until an actual question is given to me lol)
4. cheers guys!!!!

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Updated: December 10, 2010
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