求助与分享-->pumpkin转移

瑜珑

GWD的真题，请大家关注，我会陆续跟大家分享一些好东西．

Ａstring of 10 lightbubles is wired in such a way that if any individual lightbulb fails, the entire string fails. If for each individual lightbulb the probability of failing during time period T is 0.06. What is the probability that the string of lightbulbs will fail during thime period T?

A 0.06

B.(0.06)的１０次方

Ｃ．１－（０．０６）的十次方

Ｄ．０．９４的十次方

Ｅ．　１－０．９４的十次方

rabbit

the probability that the string of lightbulbs will fail during thime period T=1-the probability that the string of lightbulbs will not fail during thime period T

the probability that the string of lightbulbs will not fail during thime period T=(1-0.06)^10

so the answei is : 1-(1-0.06)^10=Ｅ．　１－０．９４的十次方

瑜珑

rabbit,谢谢你,你的答案是正确的,可是我不懂为什么非要用1去减掉NOT FAIL的，

题目中不是直接告诉我们fail 的概率是０．０６了吗，所以我就选了Ｂ．

不好意思，我的问题很弱智．

rabbit

所有的可能性为1=fail 的可能+ not fail 的可能

not fail的必要条件是每一个bulb都not fail, 1个bulb NOT FAIL 的可能是（1-0.06），那么10个都NOT FAIL（即the string of lightbulbs will NOT fail)  的可能为（1-0.06）^10。

不知我讲清楚没？

瑜珑

非常非常谢谢你,讲得很清楚,我终于搞明白了.

rabbit

You are welcome.