Question

概率问英文问题....(10分,急)

Answer 1

------------------------------------------------------------------------------------------------------ 图片参考：img716.imageshack.us/img716/7959/statisticsg 2010-11-02 12:46:28 补充： img716.imageshack.us/img716/7959/statisticsg 2010-11-02 12:48:27 补充： 第1题 有少少打错 the probability he went via route B P(via B & late ; he has been late) =(30%)(10%)/0.085=0.03/0.085=0.353 the probability he went via route C P(via C & late ; he has been late) =(20%)(15%)/0.085=0.03/0.085 =0.353 2010-11-02 14:12:45 补充： 改正 第 3 题 (3) (1)How many students scored more than 80? P(Z >2) =0.5-0.4772= 0.0228 (2)What is the probability that a randomly chosen stuent failed in the test? P(Z<-2)=0.5-.4772=0.0228 2010-11-02 14:22:27 补充： 改正第 3题 part 1 问 how many students P(Z>2)= 0.0228 0.0228 x 400 students = 9 students (corr. to the nearest integer)