GWD3-17

[邁向高等學府]

If a certain coin is flipped, the probability that the coin will land heads is 1/2. If the coin is flipped 5 times, what is the probability that it will land heads up on the first 3 flips and not on the last 2 flips?

A. 3/5
B. 1/2
C. 1/5
D. 1/8
E. 1/32

答案為E, 麻煩大家解釋一下…感恩。

[JS]

this is what I think but maybe wrong

the probability of coin flip is 1/2 for every toss, therefore for 5 toss the probability is (doesnt matter one head 4 tails or 2 heads 3 tails)
(1/2)^5 = 1/32

[michelle610]

還是不懂未什麼是Eㄟ 題目不是就有問職五次 頭朝上的要在前三次的機率ㄇ 那為什麼答案不是D

[汪汪北鼻]

前三次正面，但後二次不為正面(也就是要反面)

+++--=(1/2)^5=1/32

[michelle610]

哈哈 真是謝謝汪汪北鼻的熱心鼎力相助 非常感謝