Question 616007
If you have an 80 in a class and want to keep it the exact same then you need to get the exact same value no matter how much the exam is worth as a larger score would raise it and a lower score than 80 would lower it. The smaller the value of the exam, the less the change but it would still change if you don't get an exact 80%.

Saying that, if they are rounding up and you actually have a 79.5 or a 80.49 then a very small fluctuation may or may not change the whole number.

To calculate the new score you would need to use the following formula:

current score multiplied by 0.85 + 0.15a = 80, where a is the score of the exam to maintain an 80%.

So 0.15a = 80 - (0.85 x current mark with decimal places if available)

a = (80 - (0.85 x current mark))/0.15

If they round up from 79.5 then you could replace this number with 80 to find the absolute minimum that you will need to maintain an 80 rounded up but I doubt it would make much of a difference. To be safe you should try for an 80.