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Math Help - What am I doing wrong here?

  1. #1
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    What am I doing wrong here?

    I know it must be a small mistake and it is driving me mad! This is a question with a follow up, so be sure to read the whole thing first.

    1. Mr. Boberts gives a test, and his students’ scores range from 30 to 70. He decides to curve the scores, so that they range from 65 to 95. Let “x” be an original score, and “y” be a curved score. Using the ordered pairs (30,65) and (70,95), write the equation in slope/intercept form that he should use to curve the test scores.


    m = (65) - (95)/(30) - (70)
    m = -30/-40
    m = - (-30/40)
    m = - (-3/4)
    m = 3/4


    y = mx + b
    65 = (3/4)(30) + b
    65 = 90/4 + b
    65 = 45/2 + b
    65 + 45/2 = b
    130/2 + 45/2
    175/2 = b


    So... y = (3/4)x + 175/2


    Following up: In the scenario above, what will an original score of 62 become?


    y = (3/4)62 + 175/2
    y = 93/2 + 175/2
    y = 268/2
    y = 134

    This can't be correct...

    -Thanks will be given to those who help-
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  2. #2
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    Quote Originally Posted by bobbyboy1111 View Post
    I know it must be a small mistake and it is driving me mad! This is a question with a follow up, so be sure to read the whole thing first.

    1. Mr. Boberts gives a test, and his students’ scores range from 30 to 70. He decides to curve the scores, so that they range from 65 to 95. Let “x” be an original score, and “y” be a curved score. Using the ordered pairs (30,65) and (70,95), write the equation in slope/intercept form that he should use to curve the test scores.


    m = (65) - (95)/(30) - (70)
    m = -30/-40
    m = - (-30/40)
    m = - (-3/4)
    m = 3/4


    y = mx + b
    65 = (3/4)(30) + b
    65 = 90/4 + b
    65 = 45/2 + b
    65 + 45/2 = b ... should be 65 - 45/2 = b

    ...
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  3. #3
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    O.k., I've made my corrections. Is this correct?

    m = (65) - (95)/(30) - (70)
    m = -30/-40
    m = - (-30/40)
    m = - (-3/4)
    m = 3/4


    y = mx + b
    65 = (3/4)(30) + b
    65 = 90/4 + b
    65 = 45/2 + b
    65 - 45/2 = b
    130/2 - 45/2
    85/2 = b


    So... y = (3/4)x + 85/2


    Follow up: In the scenario above, what will an original score of 62 become?


    y = (3/4)62 + 85/2
    y = 93/2 + 85/2
    y = 178/2
    y = 89

    Please let me know! Thanks
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  4. #4
    maa
    maa is offline
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    yes you are correct.
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