How the weighting scheme works in determining your final average

Say during the semester your three exam scores were 79%, 91%, and 82%.  Your final exam score was 83%.  Drop the lowest  from the first three (79%), and average the remaining three:  (91 + 82 +83)/3 = 85.3%.  This is your exam average.

You took 10 quizzes, each graded on the basis of 10 maximum points, and your results were:  8, 9, 10, 4, 8, 8, 7, 7, 9, 10.  Drop the two lowest (the 4 and one 7), and average the rest:  (8+9+10+8+8+7+9+10)/8 = 8.625.  Now convert to % by multiplying by 100%:  8.625x100% = 86.25%  This is your quiz average.

Your nine lab scores (out of 100)  were:  93, 96, 87, 95, 84, 89, 92, 79, 93.  Drop the lowest (79) and average the rest and convert to a %.  (93+96+87+95+84+89+92+93)/8 = 91.13% is your lab average.

Attendance was taken 45 times during the semester, and each presence was worth 1 point.  Say you attended class 42 times.  There is no such thing as a drop in this category.  Your attendance average would be (42/45) x 100% = 93.3%.

The weighting scheme is 10% on quizzes, 68% on exams, 17% on lab and 5% on attendance.  These %'s are first converted to fractions and now your final weighted average is computed by

final average  =   0.10x(quiz average) + 0.68x(exam average) + 0.17x(lab average) + 0.05x(attendance average)

or in this example

final average =  0.10x(86.25%) + 0.68x(85.3%) + 0.17x(91.13%) + 0.05x(93.3%) = 86.8%

Note that you can get your current standing in the course by using the above master equation, but you must substitute your averages up to that point, not for the full semester.