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Thread: Battery

  1. #1
    Super Member harpazo's Avatar
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    Battery

    A dealer originally bought 100 identical batteries at a total cost of q dollars. If each battery was sold at 50 percent above the original cost per battery, then, in terms of q, for how many dollars was each battery sold?

    My Effort:

    A dealer originally bought 100 identical batteries at a total cost of q dollars.

    (q/100)

    If each battery was sold at 50 percent above the original cost per battery, then, in terms of q, for how many dollars was each battery sold?

    (q/100) + 50 is my answer.
    The book's answer is (3q/200).

    Where did 3 and 200 come from?
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  2. #2
    MHF Contributor
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    Re: Battery

    Quote Originally Posted by harpazo View Post
    A dealer originally bought 100 identical batteries at a total cost of q dollars. If each battery was sold at 50 percent above the original cost per battery, then, in terms of q, for how many dollars was each battery sold?

    My Effort:

    A dealer originally bought 100 identical batteries at a total cost of q dollars.

    (q/100)

    If each battery was sold at 50 percent above the original cost per battery, then, in terms of q, for how many dollars was each battery sold?

    (q/100) + 50 is my answer.
    The book's answer is (3q/200).

    Where did 3 and 200 come from?
    Most of your confusion can be cleared up if you simply WRITE DOWN what it is you mean. Make sure everything makes sense with all previous things you WROTE DOWN.

    100 batteries purchased
    q total dollars spent

    q/100 = Unit Cost of One Battery -- You should state this EXPLICITLY so you don't forget, later.

    Excess = 50% * q/100 = 50% of the unit cost of one battery. -- You should state this EXPLICITLY, so you don't forget what it is.

    Your "50" means nothing. You failed to define it and it has no reference to a percentage of any kind.

    Excess + Original Unit Cost = 50% * q/100 + q/100 = Selling Price

    Seriously, WRITE DOWN what you mean and make sure it makes sense.
    Last edited by TKHunny; Feb 9th 2019 at 06:49 AM.
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  3. #3
    MHF Contributor

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    Re: Battery

    Quote Originally Posted by harpazo View Post
    A dealer originally bought 100 identical batteries at a total cost of q dollars. If each battery was sold at 50 percent above the original cost per battery, then, in terms of q, for how many dollars was each battery sold?

    My Effort:

    A dealer originally bought 100 identical batteries at a total cost of q dollars.

    (q/100)
    Don't write a formula without saying what it is or what it means!
    Since 100 batteries cost 100 dollars, then the cost each q/100 "dollars per battery".

    If each battery was sold at 50 percent above the original cost per battery, then, in terms of q, for how many dollars was each battery sold?

    (q/100) + 50 is my answer.
    You are adding "q/100 dollars per battery" to 50 what? What units does that "50" have? The only mention of "50" is "50% above the original cost". That is certainly NOT 50 "dollars per battery"!
    You seem to be showing, in several questions you have posted, a total misunderstanding of what ""percent" means. You should repeat, over and over, "A percentage has NO meaning by itself!" A percent must always be a percent of something. Here you are calling the original cost "x". Then "50% of the original cost" is "50% of q" which is 0.5q. Rather than "q+ 50" you should have "q+ 0.5q= 1.5q". And you certainly be able to recognize that 1.5 is the same as 3/2.


    The book's answer is (3q/200).

    Where did 3 and 200 come from?[/QUOTE]
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  4. #4
    Super Member harpazo's Avatar
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    Re: Battery

    Quote Originally Posted by TKHunny View Post
    Most of your confusion can be cleared up if you simply WRITE DOWN what it is you mean. Make sure everything makes sense with all previous things you WROTE DOWN.

    100 batteries purchased
    q total dollars spent

    q/100 = Unit Cost of One Battery -- You should state this EXPLICITLY so you don't forget, later.

    Excess = 50% * q/100 = 50% of the unit cost of one battery. -- You should state this EXPLICITLY, so you don't forget what it is.

    Your "50" means nothing. You failed to define it and it has no reference to a percentage of any kind.

    Excess + Original Unit Cost = 50% * q/100 + q/100 = Selling Price

    Seriously, WRITE DOWN what you mean and make sure it makes sense.
    How can I write down anything when the question makes no sense to me?
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  5. #5
    Super Member harpazo's Avatar
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    Re: Battery

    Quote Originally Posted by HallsofIvy View Post
    Don't write a formula without saying what it is or what it means!
    Since 100 batteries cost 100 dollars, then the cost each q/100 "dollars per battery".


    You are adding "q/100 dollars per battery" to 50 what? What units does that "50" have? The only mention of "50" is "50% above the original cost". That is certainly NOT 50 "dollars per battery"!
    You seem to be showing, in several questions you have posted, a total misunderstanding of what ""percent" means. You should repeat, over and over, "A percentage has NO meaning by itself!" A percent must always be a percent of something. Here you are calling the original cost "x". Then "50% of the original cost" is "50% of q" which is 0.5q. Rather than "q+ 50" you should have "q+ 0.5q= 1.5q". And you certainly be able to recognize that 1.5 is the same as 3/2.


    The book's answer is (3q/200).

    Where did 3 and 200 come from?
    [/QUOTE]

    A nice, easy to follow reply.
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