Question 935143
I'm assuming you want to find your final overall grade (with lecture + lab grades combined in a way).


You do a <a href="http://www.mathwords.com/w/weighted_average.htm">weighted average</a> (link has an example)


So...


(weight of lab)*(lab grade) + (weight of lecture)*(lecture grade) = final grade


(0.25)*(0.871) + (0.75)*(0.836) = final grade


0.84475 = final grade



So the final grade is roughly <font color="red">84.475%</font> (around B- or B, but it will depend on the teacher). 


This is not taking into consideration any extra credit or things like the professor dropping your lowest quiz score. This is why it's best to ask the teacher directly as s/he is the only person who knows that grading system perfectly. However, <font color="red">84.475%</font> is a good estimate.