一题请教NN

morninghue · 发表于 2006-10-25 22:45:00

不盛感激

Each of the 225 balls in a certain box is either red,blue,or white and has a number from 1 to 10 painted on it. If one ball is to be selected at random from the box, what is the probability that the ball selected wil either be white or have an even number painted on it?

i)the probability that the ball will both be white and have an even number painted on it is 0

ii)the probability that he ball will be white minus the probablility that the ball with have an even number painted on it is 0.2

answer:3 either is sufficient

+	x	y	z
4	1	-5	m
e	7	n	10
f	2	-4	5

answer:m+n+5

mymengming · 发表于 2006-10-25 23:57:00

以下是引用morninghue在2006-10-25 22:45:00的发言：

不盛感激

Each of the 225 balls in a certain box is either red,blue,or white and has a number from 1 to 10 painted on it. If one ball is to be selected at random from the box, what is the probability that the ball selected wil either be white or have an even number painted on it?

i)the probability that the ball will both be white and have an even number painted on it is 0

ii)the probability that he ball will be white minus the probablility that the ball with have an even number painted on it is 0.2

answer:3 either is sufficient

+	x	y	z
4	1	-5	m
e	7	n	10
f	2	-4	5

answer:m+n+5

[attachimg]51712[/attachimg]

我觉得是E

（1）白的都是奇数的，兰和红的有一部分是奇数的，一部分偶数的，不能得出白的和偶数的总和

（2）白的-偶的=0.2，不能得出

（1）+（2）也不能得出

第二个是加的意思，就是y+4=-5，x+4=1…………

morninghue · 发表于 2006-10-27 15:06:00

谢谢!不过难道第1题答案错了?

第2题这样算下来M+N=11?

skyskywindy · 发表于 2006-10-27 15:48:00

我觉得答案对啊,either is efficient.

白球的概率+偶数的概率-既是白球又是偶数的概率=答案

题目里可以知道白球的概率和偶数的概率,给出的条件都是说既白又偶的概率.减掉就成.

morninghue · 发表于 2006-10-31 14:57:00

谢谢,但是如何解释第二个条件呢?

一题请教NN

一题请教NN

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