f6M1數學題一問?10點
2011-09-13 2:08 am
A man buys 10 raffle tickets from total of 1000 tickets,of which only 3 of tickets will win prize$800,each ticket costs $10.If all tickets are sold,find man's expected net gain.
回答 (1)
2011-09-16 9:03 am
✔ 最佳答案
Expected net gain =P(0 tickets wins among 10) * (0 - 10 * 10)
+
P(1 tickets wins among 10) * (800 - 10 * 10)
+
P(2 tickets wins among 10) * (2 * 800 - 10 * 10)
+
P(3 tickets wins among 10) * (3 * 800 - 10 * 10)
=(997C10) / (1000C10) * (- 100)
+
(997C9) (3C1) / (1000C10) * 700
+
(997C8) (3C2) / (1000C10) * 1500
+
(997C7) (3C3) / (1000C10) * 2300
= 0.970269548 * (- 100)
+
0.029461626 * 700
+
0.000268104 * 1500
+
0.000000722 * 2300
= $ - 76
收錄日期: 2021-04-21 22:22:29
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110912000051KK00462