常规-是否可以根据现有平均值并为所得平均值指定新参数来计算平均值? [英] General - Is there a way to calculate an average based off of an existing average and given new parameters for the resulting average?

问题描述

可以说，我们正在计算考试成绩的平均值:

Lets say, we're calculating averages of test scores:

初始考试成绩:75、80、92、64、83、99、79

Starting Test Scores: 75, 80, 92, 64, 83, 99, 79

平均= 572/7 = 81.714 ...

Average = 572 / 7 = 81.714...

现在给定81.714，如果您不知道初始测试分数，是否可以添加一组新的测试分数来扩展"该平均值?

新考试成绩:66、89、71

New Test Scores: 66, 89, 71

平均= 226/3 = 75.333 ...

Average = 226 / 3 = 75.333...

正常平均值将为:798/10 = 79.8

Normal Average would be: 798 / 10 = 79.8

我尝试过:

Avg = (OldAvg + sumOfNewScores) / (numOfNewScores + 1)

(81.714 + 226) / (3 + 1) = 76.9285

Avg = (OldAvg + NewAvg) / 2

(81.714 + 79.8) / 2 = 80.77

而且都没有达到应该"的确切平均值.考虑到您不知道初始值，这样做在数学上是否可行?

And neither come up the exact average that it "should" be. Is it mathematically possible to do this considering you don't know the initial values?

推荐答案

您必须知道原始组和旧平均值中的考试分数数量:

You have to know the number of test scores in the original set and the old average:

newAve = ((oldAve*oldNumPoints) + x)/(oldNumPoints+1)

这篇关于常规-是否可以根据现有平均值并为所得平均值指定新参数来计算平均值?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！