求SAT达人解答一数学问题the arithmetic mea and standard deviation of a certain normal distribution are 15.5 and 3.0,respectively.what value is exactly 1.5 standard deviations less than the mean?先告诉我问的是什么 看了半天都晕

求SAT达人解答一数学问题the arithmetic mea and standard deviation of a certain normal distribution are 15.5 and 3.0,respectively.what value is exactly 1.5 standard deviations less than the mean?先告诉我问的是什么 看了半天都晕 怎么做 求解答!SAT 数学 数学问题,求解答 SAT数学：From a jar containing 50 pieces of candy,of which 25 are red and 25 are green,Ari has taken an additional 13 pieces from the jar.What is the least number of these additional pieces that must be red in order for Ari to have more red candie 【求解答】,高一数学集合问题(填空) 高一数学,求值域问题要详细解答过程! 数学高一问题（我是菜鸟.求高手解答） 求一位能为我解答各种数学物理问题的人 我现在初二 数学问题求大神解答! 初中数学问题求解答! 初中数学问题,求解答 数学根号问题.求解答 > 数学问题,求高手解答 数学问题,求高手解答 高一数学求解答 一道数学极限问题,求解答过程 数学分类问题 求解答啦~~ 请教数学英语问题,求解答