To understand what a weighted average calculator is one must first understand what a what a weighted average is. Weighted average has nothing to do with weight conversion, but sometimes people confuse these concepts. The typical average, or mean, is when all values are added and divided by the total number of values. This can be computed using an average calculator and simply by hand or using a hand held calculator since all the values have equal weights. But what happens when values have different weights? Below you will see how to calculate the weighted average using the weighted average formula.
How to Calculate Weighted Average
One type of average which is typically always weighted is a grade point average. The GPA calculator can be used and is just a type of weighted average calculator. For example, suppose a student has two four credit classes, a three credit class and a two credit class. Here's how to calculate the GPA using a weighted average.
- Take the value assigned to the grade and multiply by the number of credits.
- Total the number of credits.
- Mutilply each grade value to the credits for that class.
- Add all the values.
- Divide by the total number of credits
Suppose the grades are as follows: A for a 4 credit class, B for the other 4 credit class, A for the 3 credit class and C for the 2 credit class. Let A = 4, B = 3 and C = 2 for values used to determine GPA. The weighted average is calculated as follows:
(4 * 4 + 4 * 3 + 3 * 4 + 2 * 2)/(4 + 4 + 3 + 2) = 3.38
Compare to to an average that is not weighted and we get
(4 + 3 + 4 + 2)/4 = 3.25. Notice how the weighted average is different. The method used to calcualte the GAP can also be known as a weighted grade calculator
Weighted Average Formula
To figure out how to calculate a weighted average we need to know the amount of weight each value has. Typically this is in the form of a percentage or in statistics, a probability of occurrence. For example, suppose a grade in a class is determined by exams, quizzes and homework assignments. Each of three exams is worth 25 percent of the grade, the quizzes are worth 15 percent and the homework assignements are wrth 10 percent. To calculate the avearge you multiply the percentage by the grades and add together. If the test scores are 75, 90, 88 , the quiz average is 70 and the homework grade is 86, the weighted average is as follows:
(0.25 * 75 + 0.25 * 90 + 0.25 * 88 + 0.15 * 70 + 0.10 * 86) = 82.35
Compare this to a non-ewighted average of
(75 + 90 + 88 + 70 + 86) = 81.8