Need Math Help!! (7th grade math)

  1. Here's the problem; I'm clueless. I know the answer from the back of the book but no idea how they got it.

    "Annette, Rita, Sharmain, and Jana compete in the 100-yard dash track-and-field event. How many different ways can the four of them finish first, second, third, and fourth? (Ignore ties.)"

    HELP! Thanks. I hate this stuff.
    •  
  2. 14 Comments

  3. by   SHELLYBELLYRN
    Is the answer 24?
  4. by   Zee_RN
    Yes, the answer is 24...how did you DO that?!
  5. by   Mkue
    Zee, is the answer 16?

    how did you guys get 24? thanks
  6. by   OBNURSEHEATHER
    Well, I got out a pencil and piece of paper and was honestly going to attempt to figure it out....

    But then I decided I simply didn't have the energy...

    So do tell Shelly, how'd ya get 24? I'm thinking your baby is gonna be a little genius!

    Heather
  7. by   Zee_RN
    OK, I got the answer but not on my own, LOL!

    The answer is 24 and the calculation is 4 x 3 x 2 x 1. How they KNEW that, I have no idea.

    If the runners were assigned letters ABCD, it would come out like this:

    ABCD, ABDC, ACDB, ACBD, ADBC, ADCB
    BACD, BADC, BCAB, BCDA, BDAC, BDCA,
    CABD, CADB, CBDA, CBAD, CDAB, CDBA
    DABC, DACB, DBAC, DBCA, DCAB, DCBA

    WHEW!!! Now, except for kids' homework, when am I going to need to KNOW this?!
  8. by   SHELLYBELLYRN
    OK........I just remembered this thingy from math...........where if you need to know the # of combinations possible (assuming they could all be arranged in any order....) then you multiply the # of factors (4) x every # below it.............

    Like there are 4 competitors...........so 4x3x2x1= 24.........

    does that make ANY sense?
  9. by   Mkue
    Cool, I only had them running 16 races, guess I wouldn't be a very good track coach..lol

    OK, I'm ready for another question.
  10. by   Zee_RN
    Thanks, Shelley, it helps to know the rule!

    You want another, mkue? There was another one that I puzzled over...
  11. by   meandragonbrett
    you do 4! if you said it outloud that would read "Four factoral" which the "!" means you do 4x3x2x1

    Brett
  12. by   OBNURSEHEATHER
    Originally posted by mkue
    Cool, I only had them running 16 races, guess I wouldn't be a very good track coach..lol
    LMAO! :chuckle

    Heather
  13. by   SHELLYBELLYRN
    Thanks, Brett.............couldn't remember it was called "factoral"............been a while since I was in math class............I can remember HOW to do it, but not WHY
  14. by   OBNURSEHEATHER
    Hmm. I don't remember and "!" being part of math class, but I was a big haired cigarette smoking rebel, so it's entirely possible I missed it.

    Good to know though

    Heather

close