[問題]天山03-23

[feebs79]

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

Answer: B

不是每次toss就有1/2的機會是正面(or反面)
so三次就1/2*1/2*1/2=1/8不是嗎?所以我選A

請問我邏輯錯在哪?

謝謝!

[kwtluck]

妳忽略了題目說on the same side each time
所以還要選是正面or背面
C2取1*1/2*1/2*1/2=1/4