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A simple qestion

  1. Dec 22, 2014 #1

    Firedog89

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    Three of four numbers have a sum of 22. If the average of
    the four numbers is 8, what is the fourth number?
    A. 4
    B. 6
    C. 8
    D. 10
     
    Firedog89, Dec 22, 2014
  2. jcsd
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  3. Dec 22, 2014 #2

    Maged Saeed

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    apply the average rule:

    the sum of all the numbers / the number of the numbers

    you would get only one unknown to find.
     
    Maged Saeed, Dec 22, 2014
  4. Dec 22, 2014 #3

    Firedog89

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    I'm not given the other 3 numbers. I think I'm misinterpreting what you are saying sum/amount of numbers or sum/each number totaled up. 22/4=5.5 evenly distributed. I'm also running into an issue also one of the numbers doesn't necessarily have to be 8 the 4 numbers average is 8.

    oh wait 3 of 4 numbers have a sum of eight. 6,7,, and 9=22 so the 4th number has to be 8. but 22/3=7.3 I mean visually it makes sense but mathematically I'm not getting the answer.
     
    Last edited: Dec 22, 2014
    Firedog89, Dec 22, 2014
  5. Dec 22, 2014 #4

    ehild

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    The average of the four numbers is 8. What is the sum of the four number?
     
    ehild, Dec 22, 2014
  6. Dec 22, 2014 #5

    Firedog89

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    Would that be (22+x)/4=8 ok I got 10. Thanks. I just had to think a bit more straighter. :)
     
    Firedog89, Dec 22, 2014
  7. Dec 22, 2014 #6

    ehild

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    Correct! You could have done it without writing an equation.. if the average of N number is A, the sum of them is NA. The average of 4 number is 8, then the sum of them is 32. .But the sum of three of them is 22, and adding the fourth yields 32...
     
    ehild, Dec 22, 2014
  8. Dec 22, 2014 #7

    Firedog89

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    I don't know, I think I work better by writing down equations or just writing everything down.
     
    Firedog89, Dec 22, 2014
  9. Dec 22, 2014 #8

    Dale

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    Staff: Mentor

    Please use the template and show some effort.
     
    Dale, Dec 22, 2014
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