I have a math exam tomorrow. My current overall-average is $98\%$(A). The exam will be $15$ OR $20\%$ of the final grade. What percentage would I need on this exam to get at least $90\%$ (A-) as a final year grade?
The calculation I think for $20\%$ looks like this:
$(0.80 \cdot 98)+(0.20 \cdot x)=90$
I calculated this equation for both $20$ and $15\%$, but I get for $20\%$ a smaller amount than for $15\%$, which makes me feel kind of "perplexed."
Can you check and explain how to calculate this?
Thank you!
You want either
$(0.80 * 98) + (0.20 * x) = 90$
or
$(0.85 * 98) + (0.15 * x) = 90$
since the exam you have tomorrow and what you have done so far must add up to 100% of the mark.