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Another Maths conundrum
5 Answers
The end result is 60%. This is the result of 2 marks one weighted at 40% the other at 60% -how do I calculate the 2 original marks?
(I only got grade 1 CSE maths back in 1973 and this has flummaxed me!!)
(I only got grade 1 CSE maths back in 1973 and this has flummaxed me!!)
Answers
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For more on marking an answer as the "Best Answer", please visit our FAQ.There is not just one solution to this problem. If you know the mark obtained in one test then you can calculate the mark required in the othe test to give the overall target grade.
You work out the relationship as follows:
Let x = mark out of 100 in the first test
Let y = mark out of 100 in the second test
Now 40% of x + 40% of y = 60
or 40x/100 + 60y/100 = 60
multiply throughout by 100
40x + 60y = 6000
4x + 6y = 600
2x + 3y = 300
Rearranging
x = (300 - 3y)/2
or
y = (300 - 2x)/3
Example sets of solutions:
x = 0, y = 100
x = 75, y = 50
You work out the relationship as follows:
Let x = mark out of 100 in the first test
Let y = mark out of 100 in the second test
Now 40% of x + 40% of y = 60
or 40x/100 + 60y/100 = 60
multiply throughout by 100
40x + 60y = 6000
4x + 6y = 600
2x + 3y = 300
Rearranging
x = (300 - 3y)/2
or
y = (300 - 2x)/3
Example sets of solutions:
x = 0, y = 100
x = 75, y = 50