SOLUTION: In how many distinct ways can the letters of the world ATLANTA be arranged?

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Question 1188357: In how many distinct ways can the letters of the world ATLANTA be arranged?

Found 2 solutions by Edwin McCravy, MathLover1:
Answer by Edwin McCravy(20055) About Me  (Show Source):
You can put this solution on YOUR website!
If all 7 letters were distinguishable, the answer would be 7!
But since the 3 A's are not distinguishable, 3! of the 7! look alike, so we divide by 3!, and get 7!/3!

Since the 2 T's are not distinguishable, 2! of the 7!/3! look alike, so we also divide by 2!

Answer: 7%21%2F%283%212%21%29%22%22=%22%22%287%2A6%2A5%2A4%2A3%2A2%2A1%29%2F%28%283%2A2%2A1%29%282%2A1%29%29%22%22=%22%22420

Edwin

Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

There are 7 letters, so there are 7%21 ways in arranging 7} objects into 7 spaces.
But we've overcounted by a factor of 3%21 (a's can interchange in 3%21 ways), and
2%21 (t's can interchange in 2%21+ways).
To better understand this concept, let's name each repeated letter:
a%5B1%5D +t%5B1%5D +l a%5B2%5D n +t%5B2%5D++a%5B3%5D
Now, we can rearrange Atlanta to make:
a%5B2%5D +t%5B2%5D l a%5B3%5D n t%5B1%5D a%5B1%5D
Without the superscripts, we make Atlanta.
But, we've already made that word with:
a%5B1%5D +t%5B1%5D +l a%5B2%5D n +t%5B2%5D++a%5B3%5D
This is because we need to account for the times the+a's can change and we wouldn't notice, and the t's can change and we won't notice.
Thus, our final number of ways becomes:
7%21%2F%283%212%21%29=420 different ways