Simple Math Question

Discussion in 'Physics & Math' started by deicider, Mar 1, 2011.

  1. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    Uh, okay. How about this one:
    What is the cost of a rocket that costs 1$ plus half of its price?

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  3. Mrs.Lucysnow Valued Senior Member

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    How is half the price of $1 two dollars?
     
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  5. Tach Banned Banned

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    ONE of the MANY possible answers is 2$. This is an example of an incorrectly stated problem. As such, it can have multiple, CONTRADICTING answers: 1$, 1.5$, 2$ are equally valid answers.
     
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  7. Emil Valued Senior Member

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    Strictly mathematically is given:
    C = P / 2 +1
    We still need a relationship to solve the equation.
     
  8. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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  9. adoucette Caca Occurs Valued Senior Member

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    No Tach, it's a simple math problem for which you apparently couldn't figure out the correct answer.

    There is absolutely no basis for the answer YOU came up with: $1.50.

    No matter how you parse the problem there was no reference to a second book as you suggested.

    Arthur
     
  10. adoucette Caca Occurs Valued Senior Member

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    Lucy, the question is: What is the cost of a book whose cost is $1 PLUS half of it's price?

    So let's parse this:

    The essential question being asked is: What is the PRICE of the Book?

    We will call this unknown Price of the book X

    What we are told is the PRICE of the book or X is made up of TWO components.

    A fixed value of $1 and half the value of X.

    So we can now write the formula.

    X = $1 + 1/2X

    We subtract 1/2X from both sides and get

    1/2X = $1

    We multiply both sides by 2 and get

    X = $2

    So the price of the book is $2.



    Of course, when people on the internet get the problem wrong they start attacking the PROBLEM and invariably refuse to acknowledge that their math skills are simply rusty. You can spot these posers because when they get it wrong they start talking about cost not being the same as price, while even a kid knows when they ask how much something costs they are told the price.

    Arthur
     
  11. Emil Valued Senior Member

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    This is a good one.

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    But what about 22?
     
  12. Mrs.Lucysnow Valued Senior Member

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    Okay you say we are told X is made up of two components.

    Where is the second component? We have one dollar plus something else (x) which is half of the original price. Why do we have to multiply anything?

    I'll admit math isn't my strong suit but I didn't think the sentence was so loaded that there would be a need for any multiplying.
     
  13. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    19,252
    Yeah. But how much was the rocket?
     
  14. Tach Banned Banned

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    He'll never figure it out

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  15. adoucette Caca Occurs Valued Senior Member

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    Well it's just a math technique to get one side of the equation to just be X.

    So if you again look at the problem we boiled it down to this:

    The final price of the book was equal to $1 plus half of the price of the book:

    Which we wrote like this, using X as the price of the book:

    X = $1 + 1/2X

    So first of all we want to get X on just one side of the equal sign, which we do by performing the exact same operation to both sides of the equal sign. (by the way that is something that is always allowed, you can perform any operation you want, as long as you do it on both sides of the equal sign)

    So, to get rid of the 1/2 X on the right, we subtracted 1/2 X from each side.

    or

    X - 1/2X = $1 + 1/2X - 1/2X

    Which gets rid of X from the Right side of the equation and results in

    1/2 X = $1

    But we really need to know what 1 X is (the price), not 1/2 X, so to do that we again perform the exact same operation to both sides of the equal sign.

    This time though, what we do is multiply both sides by 2 which of course will turn the 1/2 X into just 1 X.

    1/2 X * 2 = $1 * 2

    Which results in the final answer

    X = $2

    Hope this helped (By the way, I know most of us don't use even this level of math in our day to day lives, so no worries)

    Arthur
     
  16. gmilam Valued Senior Member

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    3,522
    This is an easy problem. The fact that so many are having difficulty with it is somewhat disturbing...

    $2.00
     
  17. Expansion Registered Member

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    24
    Hold on is this one of those questions that just keeps going to infinity?
    eg) 1 + 1/2
    1.50 + 1.50/2
    2.25 + 2.25/2
    .....
     
  18. James R Just this guy, you know? Staff Member

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    39,397
    adoucette's answer is correct. "Cost" and "price" can safely be taken to be synonymous. The answer is $2.

    There's no mention of two books in the original problem statement. You're reading things into this that aren't there.

    No. As stated, the only sensible answer is $2.

    If you want to argue something else, you'll need to do better than "there were really two books, not one".
     
  19. James R Just this guy, you know? Staff Member

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    No. Let cost/price be x.

    Then the cost is x = 1+x/2.
    Basic algebra then gives x=2. Done.
     
  20. Tach Banned Banned

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    The OP tells you, NO. Quite a few of us showed why, read the thread.
     
  21. Tach Banned Banned

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    Err, no. Cost and Price are two different things. Otherwise, the whole economy would go to pot.

    So, the correct equation is:

    y=1+x/2

    Which has an infinity of solutions.
     
  22. rpenner Fully Wired Valued Senior Member

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    Within the context of an economics textbook geared at those who have already mastered algebra beyond these interpretations. This suggests that you are engaged in the equivocation described as a semantic shift.

    And no-one wants to be labelled anti-semantic.

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  23. James R Just this guy, you know? Staff Member

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    I read it. It's straightforward, like I said.

    Not in this context.

    So, the OP asks a question that has no answer. How likely is that?

    Or is it more that you can't come up with a simple answer?

    It reminds me of your dismal effort in [thread=105775]this thread[/thread]. where you also claimed that I was wrong, but eventually wimped out.
     

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