GWD-1-2滔滔

tania_zhang

Q2:A certain roller coaster has 3 cars, and a passenger is equally likely to ride in any 1 of the 3 cars each time that passenger rides the roller coaster.
If a certain passenger is to ride the roller coaster 3 times, what is the probability that the passenger will ride in each of the 3 cars?

A.
0

B.
1/9

C.
2/9

D.
1/3

E.
1

这个题答案不是1/3*1/2=1/6么，c怎么算出来的？

xiruihuang

首先,你要知道这道题的答案需要把每一辆车被选择一次的概率相乘.那么第一辆车可任选即概率为1,第二次在三辆车中选另两辆未被选过的车中的一辆的概率为2/3,最后一次在三辆车中选唯一一辆未被选过的车的概率为1/3: 1*2/3*1/3=2/9

tania_zhang

知道了，我之前解题思路错了-分母搞错了，应该是:（C13*C12 *1）//(3*3*3)=2/9谢谢楼上

xiaotangyu

我的理解是：C33*1/3*1/3*1/3=2/9

rosswye

我的理解是：C33*1/3*1/3*1/3=2/9
xiaotangyu 发表于 2010-8-16 06:37

    per your comprehension the answe is 1/9,LZ is right.

tania_zhang

many  thanks!!!