ChaseDream

标题: Gmat prep Maths-谢谢 [打印本页]

作者: xiaotou 时间: 2006-10-13 10:11
标题: Gmat prep Maths-谢谢

On his way to work, Leo listens to one of three radio stations, A, B, or C. He first turns to A, if A is playing a song he likes, he listens to it; if not, he turns to B. If B is playing a song he likes, he listens to it, if not he turns to C. If C is playing a song he likes, he listens to it, if not, he turns off the radio. For each station the probability is 0.3 that at any given moment the station is playing a song he likes. On his way to work, what's the probability that Leo will hear a song he likes. ( answer: 0.657)

此题无思路，请各位帮助

作者: liuyang1984 时间: 2006-10-13 10:17

看错题了，嘿嘿

最先听a频道，遇到喜欢的歌的可能性是0.3

如果a 频道的不喜欢，听b频道，可能性为0.7*0.3，因为a频道的不好听

类似听c频道是0.7*0.7*0.3

加起来就是答案了

[此贴子已经被作者于2006-10-13 10:21:29编辑过]

作者: Shadowx 时间: 2006-10-13 12:31

更簡單的方法：

1-關機的機率=碰到好聽歌曲的機率

1-(3/10)^3 = 1 - 343/1000 = 0.657

作者: xiaotou 时间: 2006-10-13 21:08
thank you!

作者: 米可可 时间: 2006-10-13 22:03

以下是引用Shadowx在2006-10-13 12:31:00的发言：

更簡單的方法：

1-關機的機率=碰到好聽歌曲的機率

1-(3/10)^3 = 1 - 343/1000 = 0.657

应该是1-（7/10）^3

欢迎光临 ChaseDream (https://forum.chasedream.com/)