天山3-23的正确答案是什么？

insonbia13

Q23:
When tossed, a certain coin has equal probability of landing on either side. If the coin is tossed 3 times, what is the probability that it will land on the same side each time?

A. 1/8
B. 1/4
C. 1/3
D. 3/8
E. 1/2

这题的答案是A 还是B啊？我觉得应该是Ａ啊

apply1

答案是B,

我开始也选的是A,但是三次投掷，全是正面朝上的几率是1/2 * 1/2 * 1/2=1/8， 全是反面朝上的几率也是1/8，所以结果是同一面的几率相当于是1/8+1/8=1/4

不知道怎么解释对不对