A weighted grade is not an ordinary mean unless every item has the same weight. Convert each percentage weight to a fraction of 100, multiply it by the score, and add the resulting course points. Keep the total entered weight beside the answer: it determines whether you have a complete course result or only a snapshot of graded work.
Calculate course-point contributions
For a score of 92% with a 20% weight, the contribution is 92 × 0.20 = 18.4 course points. A score of 84% weighted at 15% contributes 12.6 points. Repeat this multiplication for every row before adding anything. This preserves the intended importance of each activity and makes a mistaken weight easy to spot.
Distinguish course points from current average
If entered weights total 70%, adding contributions gives the points already secured out of the full course. Dividing that sum by 70 and multiplying by 100 gives the normalized average on graded work. These numbers answer different questions and should not be silently substituted. When weights reach 100%, the course points and normalized percentage coincide.