Summarize the following:
You’ll need to start by assembling a list of the numbers for which you’d like to find the weighted average. For example, if you’re trying to find a weighted average for a series of grades in a class, first write down each of the grades. For instance, maybe your total grades are 82 for quizzes, 90 on your exam, and 76 on your term paper. Once you have your numbers, you’ll need to know how much each of them weighs, or is worth, as part of your final average. For instance, in your class, the quizzes might be worth 20% of your total grade, while the exam is 35% and the term paper is 45%. In this case, the weights add up to 1 (or 100%). In order to use these percentages in your calculation, you’ll need to convert them to decimal form. The resulting numbers are called “weighting factors.” Once you have all your numbers, pair up each number (x) with its corresponding weighting factor (w). You’ll be multiplying each set of numbers and weights together, then adding them all up to find the average. For example, if your total quiz score is 82 and quizzes are worth 20% of your grade, multiply 82 x 0.2. In this case, x=82 and w=0.2. The basic formula for a weighted average where the weights add up to 1 is x1(w1) + x2(w2) + x3(w3), and so on, where x is each number in your set and w is the corresponding weighting factor. To find your weighted average, simply multiply each number by its weight factor and then sum the resulting numbers up. For example: The weighted average for your quiz grades, exam, and term paper would be as follows: 82(0.2) + 90(0.35) + 76(0.45) = 16.4 + 31.5 + 34.2 = 82.1. This means you have a grade of 82.1% in the course.
Gather the numbers you would like to average. Determine the weight value of each number. Multiply each number by its weighting factor (w). Add the resulting numbers together to find the weighted average.