data groupA: 40 students, mean mark=50, standard deviation=15
data groupB: 40 students, mean mark= 40,standard deviation=10
if data group A is combined with data group B, what's the new mean and standard deviation?explain
收錄日期: 2021-04-19 20:44:38
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20091130000051KK01414