# Equation in matrix

1. Mar 11, 2005

### carltonblues

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)

a)
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

and...

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. Mar 12, 2005

### SpaceTiger

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