Expert: Sherry Wallin - 5/16/2011

Question
I'm wanting to plug in final exam scores into an equation to find my final grade in one class.  My grade right now is a 96, and my final exam I'm taking tomorrow is 20% of that.  The final exam is 200 questions, and each question is worth .5 points.  How do I figure out how many questions I can miss without getting a B?

Answer
Katie~

If I understand you correctly, you have 96% but only 80% of your grade is calculated with that. So one way to first see what is the lowest score you can get and still get an A is to write this equation:

x = the minimum number of points necessary to get an A in the course

.8(96) +.2x >=90  =>
76.4 + .2x >= 90 =>
.2x >= 13.6 =>
x >= 68

So since there are 200  questions @ .5 points each there will be a total of 100 points and you need at least 68 points => 136 questions answered correctly which is saying that you can miss no more than 64 of the questions in order to still get an A.  

Math Prof