How to Calculate Weighted Average

Want to determine your grades for a class or need to find batting stats for a favorite player? Figure out those averages for yourself using these simple steps.

Instructions

  • TIP: For example, if the average of five test scores worth 25 percent of the total grade were 90 percent, you would multiply the average of the scores, 90, by the weight, 0.25, to find the weighted average of 22.5 points.
  • Step 1: Add the weighted averages of each group to determine the total weighted average.
  • FACT: As of 2010, baseball hall-of-famer Ty Cobb held the highest career batting average of all time: .366.
  • Step 2: Determine the weighted averages of each group of data by multiplying the average of all data within the group by the weight. Write the weighted average next to the data group.
  • Step 3: Convert each weight to a decimal by dividing the percentage by 100 and removing the percent sign. In the case of the test scores, this would be .25.
  • Step 4: Convert any scores not that is not in percent to a percent value.
  • TIP: For example, convert 35 out of 40 converts to a percentage by dividing 40 by 35 and converting the decimal answer, 0.875, to 87.5 percent.
  • Step 5: Find the average for data within each weighted group. For example, multiple test scores that are worth 25 percent of a total grade should be added and then divided by the number of total scores in that group.
  • Step 6: Identify the data and the percentage weight for each piece. For example, test scores that are worth 25 percent of your grade, quiz scores worth 35 percent, and homework that is worth 40 percent.

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