[機統] Bayes's定理-北科大電通所甲組消失
題目 :
A die tossed and the nimber of dots N1 is noted an integer N1 is
then selected at random from {1,2...,N1}
(a) Find the probability of the event {N2 = 3}
(b) Find the probability of {N1=4} given {N2=5}
解答 :
(a) P{N=3} = P{N2=3|N1=1}P{N1=1} +
P{N2=3|N1=2}P{N1=2} +
P{N2=3|N1=3}P{N1=3} +
P{N2=3|N1=4}P{N1=4} +
P{N2=3|N1=5}P{N1=5} +
P{N2=3|N1=6}P{N1=6}
= 0 + 0 + 1/3 + 1/4 + 1/5 + 1/6
= 19/120
想請問一下，為何 P{N2=3|N1=1}P{N1=1} = 0
P{N2=3|N1=2}P{N1=2} = 0
N2到底是甚麼東西呢，謝謝!!
(b) 0
--
※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 36.225.169.160
※ 文章網址: https://www.ptt.cc/bbs/Math/M.1482856528.A.4D8.html
推
12/28 02:33, , 1F
12/28 02:33, 1F
→
12/28 02:33, , 2F
12/28 02:33, 2F
→
12/28 02:33, , 3F
12/28 02:33, 3F
→
12/28 02:34, , 4F
12/28 02:34, 4F
→
12/28 02:34, , 5F
12/28 02:34, 5F
→
12/28 09:01, , 6F
12/28 09:01, 6F