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anonymous

  • one year ago

How many strings of eight uppercase English letters are there if no letter can be repeated?

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  1. zepdrix
    • one year ago
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    I'm taking Combinatorics right now, so I NEED to be able to answer a question like this by next week's test lol grrr, it's giving me some trouble though >.< thinking...

  2. zepdrix
    • one year ago
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    |dw:1442540278852:dw|Oh maybe this is simpler than I'm making it. So we have 26 options for the first letter, ya? Any uppercase letter from the English alphabet.

  3. zepdrix
    • one year ago
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    Let's say that first letter is an F. Then none of the other following 7 spaces can include an F. Meaning that for our next space we have 25 letters to choose from.|dw:1442540418212:dw|\(\large\rm 26-F=25\)

  4. zepdrix
    • one year ago
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    So maybe the next letter is an O. So now we can't include F or O for the remaining places. \(\large\rm 26-F-O=24\)

  5. anonymous
    • one year ago
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    i know the answer.

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