For demonstration purposes, consider a gradebook with a Homework Category and the following 2 grades:
HW1- Factor of 2: Grade of 9 out of 10
HW2- Factor of 1: Grade of 4 out of 5
  1. Is the category calculated by Total Points or Percentages?
    1. Open the gradebook, select Setup, and click Categories. 
    2. Verify whether the category uses Total Points or Percentages in the Calculation Type column.

      Using Total Points: Sum of (Awarded points * factor) / Sum of (Possible Points * Factor)
      (9 * 2) + (4 * 1) / (10 * 2) + (5* 1)= 88
       
      Using Percentages: Sum of [(Awarded points/attempted points)*factor]/Sum of Factors
      [(9/10) * 2 + (4/5) * 1] / 3 = (180 + 80) / 3 =  86.67
       
  2. Check the assignment factors
    Based on the calculations above, the assignment factors play an integral role in the result of a category average. Refer to How to setup assignments with factors.
     
  3. Does the category allow for any grades to be Dropped
    1. Open the gradebook, select Setup, and click Categories.
    2. Does a value exist in the Number to Drop column? If assignment grades are allowed to be dropped, the lowest assignment grade will not be applied to the category average.
       
  4. Verify that the maximum points assigned to the assignment is correct.  Whether the category is defined to use Percentages or Total Points, the Maximum points allowed are used in the calculation.
    1. Open the gradebook, select Setup, and click Assignments from the left navigation bar.
    2. For each assignment enter the appropriate points in the Maximum Points column.
     
  5. Make sure all assignments are associated with the correct category:
    1. Open the gradebook, select Setup, and click Assignments from the left navigation bar.
    2. For each assignment select the appropriate Category in the Category column. 
     6. Refresh the gradebook to force the grades to recalculate for the marking column:
              a. Gradebook, click Edit categories
              b. Select the correct class and marking column
              c. Change the number to drop from it's original setting to another number
              d. Click Save
              e. Change the number to drop back to its original setting
              f. Click Save