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anonymous

  • 5 years ago

In how many ways can 2 singers be selected from 10 who came to audition?

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  1. amistre64
    • 5 years ago
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    10 for the first spot, and 9 left for the second spot = 10*9, or 10P2

  2. anonymous
    • 5 years ago
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    45

  3. anonymous
    • 5 years ago
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    or 10 "nCr" 2 = 45

  4. amistre64
    • 5 years ago
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    good idea, wrong application i believe

  5. amistre64
    • 5 years ago
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    this isnt a nCr, its an nPr

  6. anonymous
    • 5 years ago
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    i don't understand how it's not 90, because that's what i did to. how do I knew when i can and cannot use that process amistre did?

  7. anonymous
    • 5 years ago
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    know*

  8. amistre64
    • 5 years ago
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    whenever you have to pick from a number of applicants, its P for "pick" in my eyes

  9. amistre64
    • 5 years ago
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    whenever the order doesnt matter, then its groups that count. nCr for groupings

  10. amistre64
    • 5 years ago
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    10 Pick 2 = 10P2 = 10*9 = 90

  11. anonymous
    • 5 years ago
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    This should be \(\binom{10}{2} = 45 \)

  12. anonymous
    • 5 years ago
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    Fair enough, I've never had to use P... Whenever I've done this in stats (ie with Binomial distribution) it's been nCr...

  13. anonymous
    • 5 years ago
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    How does the order matter in this, isn't it just saying 2 singers?

  14. amistre64
    • 5 years ago
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    i could be wrong, depends on how you interpret the question

  15. amistre64
    • 5 years ago
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    if you have 2 people that are auditioning; then you need to pick 1 for the 1st and 1 for the 2nd

  16. anonymous
    • 5 years ago
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    the answer is 45 i know that for sure, just trying to understand

  17. amistre64
    • 5 years ago
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    joe then sally is a different order than sally then joe

  18. anonymous
    • 5 years ago
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    oh okay

  19. anonymous
    • 5 years ago
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    No, as there are many different ways of picking 2 people from a bag of 10, which is different from picking 10 from a bag of 2...

  20. anonymous
    • 5 years ago
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    amistre, >>In how many ways can 2 singers be selected from 10 who came to audition? "selected" is the keyword here.

  21. amistre64
    • 5 years ago
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    i can see that interpretation as well :)

  22. anonymous
    • 5 years ago
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    But unfortunately 10P2 doesn't seem to be the correct interpretation here. :(

  23. amistre64
    • 5 years ago
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    right, then if it aint 90, go 45 ;)

  24. anonymous
    • 5 years ago
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    how do i put this into a calculator? its not 10!2 is it because that doesn't work

  25. amistre64
    • 5 years ago
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    10P2/2!

  26. anonymous
    • 5 years ago
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    the button that looks like nCr you would type 10 'nCr' 2

  27. amistre64
    • 5 years ago
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    sooo 10!/2!(10-2)! perhaps?

  28. anonymous
    • 5 years ago
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    which gives you an answer of 45.

  29. anonymous
    • 5 years ago
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    or the factorial method, yes!

  30. amistre64
    • 5 years ago
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    10*9*8*7*6*5*4*3*2 ------------------ 8*7*6*5*4*3*2*2

  31. anonymous
    • 5 years ago
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    sorry i totally forgot how to do this. when i click permutations it puts in nPr() on the screen. where do i put the 10 and 2? and why is it 10 and 2 instead of 2 then 10?

  32. anonymous
    • 5 years ago
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    It is 10C2 because 10 (n) is the number of values and 2 (c) is the number you are choosing.

  33. anonymous
    • 5 years ago
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    I don't know how you would do it in that format, you know your calculator best.

  34. anonymous
    • 5 years ago
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    so its combination or permutation?

  35. anonymous
    • 5 years ago
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    ok its a combination because the order does not matter. i did this and got 45.

  36. anonymous
    • 5 years ago
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    That's right.

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