新GRE数学要点:AT least One

会计考友

　AT least One 　　If probability of event A happening is p and event B happening is q, then the probability that at least one of them happens is (p+q).
　　Example:
　　There are 20 quarters, 33 nickels, and 47 pennies in a jar. The probability that a randomly selected coin is a quarter= 20/(20+33+47)=20/100=0.2 and the coin is nickel = 33/100 =0.33.The probability it is either a quarter or a nickel = 0.2+0.33=0.53.
! E7 y. z  E% X" M* {　　Remember:
　　The events needs to be mutually exclusive, that is if one happens the other cannot happen: a coin is either a quarter or nickel but not both.
+ `$ D, f% Z, K+ ]( Q: ~" \. S6 z1 N　　由于美国数学基础教育的难度增加导致数学考试越来越难，但新gre数学复习考点都是高中时候学到的知识点，考生不要过于紧张，把基本概念弄明白，再记住一些新版gre数学必备的词汇，那么相信新版gre数学应该没有问题。