请问谁会这2道数学，谢了！

onroad

1.袋中4个球，A，B，C，D四种颜色， 求任取出两个，其中有一个为A或B颜色球的概率？ 2.Z,X是整数，绝对值>1，问Z的X次方是否小于1？ （1）X<0 （2）Z的Z次方<1 为什么答案是A，D不对？

lisaislisa

1. 1/2 the possibility to pick each of the color is 1/4 1/4+1/4=1/2 2.Z,X是整数，绝对值>1，问Z的X次方是否小于1？ （1）X<0 （2）Z的Z次方<1 ------------------ 1)=>Z^X<1 2)=>only Z<-1 , if Z=-2,X.=2 then Z^X>1 but, if Z=-2, X=3 then Z^X<1 ^^

onroad

hi, lisaislisa,
Thank you for your reply!
the first question's answer is 5/6

yvonnezenith

第一题我有疑问。任取出两个，共有AB,AC,AD,BC,BD,CD六种。题目要求是一个为A或B颜色球，如果AB也算的话，概率应该是5/6啊。AB不算的话，概率是4/6。AB算不算啊？

lisaislisa

sorry , my mistake!
1. i think 2/3
(2*C1,2)/C2,4
since 一个为A或B颜色球 i don't think AB should be included...
your idea ?

^^

giraff

i think AB should be included, for one is A or B, the question does not tell which color the other one is .so it may be A or B too.

isenetlab12

1.( C4,2-1)/C4,2=5/6
since 任取出两个，其中at least有一个为A或B颜色球的概率=excluding the situation C and D are chosen together.

lisaislisa

not at least A , B
but A or B

^^

onroad

Thanks for all the discussion!