[問題] 擲骰子問題
Two fair eight-sided dice are rolled independently
(each is numbered from 1 to 8)
(a) What is the probability that neither one is 1 or 2 ?
(b) If the two faces are different, what is the probability that neither
one is 1 or 2 ?
我的想法：
(a)
設 P(E) = 第一次擲出1或2點骰子的機率
P(F) = 第二次擲出1或2點骰子的機率
所求為 P(E的補集∩F的補集)
= P(E∪F)補集 = 1 - P(E∪F)
又 P(E∪F) = P(E) + P(F) - P(E)P(F) (因為獨立)
= 1/4 + 1/4 - (1/4)*(1/4) = 7/16
所求 = 1 - 7/16 = 9/16 #
(b) 骰子點數不同情況下，沒有出現1或2的機會
6 * 5 30 15
= ──── = ── = ──
8 * 7 56 28 #
再麻煩一次大家幫我看一下 Orz
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11/25 19:50, , 1F
11/25 19:50, 1F