后天考试！请教1道PREP的数学！！

bigfourGAKKI

问题1：On his drive to work, Leo listens to one of three radio stations, A, B, and 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 Leo likes. On his drive to work, what is the probability that Leo will hear a song he likes?

A.0.027

B.0.09

C.0.417

D.0.657

E.0.9

答案是D。麻烦谁能帮我解答下？

问题2：例如-10，-20等，是10的倍数吧？0也是10的倍数吧？

谢啦！

spyda

问题1: 用1-0.7×0.7×0.7=0.657   这题跟上个月机经里的那个串联的电灯泡很像  只要求出三个台都不播放LEO喜欢的音乐的概率 然后用1减去  

问题2 是的

bigfourGAKKI

明白了 谢啦！

xia377

也可以这么解： 0.3+0.7*0.3+0.7*0.7*0.3=0.657