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Homework Help: Equation in matrix

  1. Mar 11, 2005 #1
    Anne is a maths student. She has achieved marks of 9 outof 10 for tutorials and 17 out of 25 for her mid semester esam. There are two options for calculation of her final mark. Both options give Annie a final mark of exactly 72%.

    F=(t + a + 0.75e)
    F=(t + a + m + 0.5e)

    Let a be Anne's assignment mark (out of 15) and let e be her final exam mark (out of 100). Write down an equation for her final mark calculation under each option::

    For that I get:

    72 = 9 + a + 0.75e
    63 = a + 0.75e


    72 = 9 + a + 17 + 0.5e
    46 = a + 0.5e

    Is that right?

    b) Use matrices to determine Anne's assignment mark and her final exam mark...

    For that i get:

    |1, 0.75|
    |1, 0.5 |

    and to find a and e you have to times the inverse and the fraction of ad-bc (-1/4) by 72 and 46. When I do this i get a and e to equal absolutlynothing near what they should be. Have i made a mistake somewhere??
    Last edited: Mar 11, 2005
  2. jcsd
  3. Mar 12, 2005 #2


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    Staff Emeritus
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    Gold Member

    I think you mean 63 and 46. That gives me 12 and 68 for a and e.
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