作十題四選一的選擇題,假設每題都不會: (a)猜對五題的機率 ? (b)猜對至少四題的機率 ? (c)平均猜對幾題 ? 以上請附算式~求解答 感謝?
回答 (2)
2015-12-06 12:07 pm
二項分配 b(n,p) = b(10,1/4)
(a) C(10,5)(1/4)⁵ * (3/4)⁵ = 0.0584
(b) 1 - C(10,0)(1/4)º * (3/4)¹º
- C(10,1)(1/4)¹ * (3/4)⁹
- C(10,2)(1/4)² * (3/4)⁸
- C(10,3)(1/4)³ * (3/4)⁷
= 0.224
(c) E(X) = np =10*1/4 =2.5
(a) C(10,5)(1/4)⁵ * (3/4)⁵ = 0.0584
(b) 1 - C(10,0)(1/4)º * (3/4)¹º
- C(10,1)(1/4)¹ * (3/4)⁹
- C(10,2)(1/4)² * (3/4)⁸
- C(10,3)(1/4)³ * (3/4)⁷
= 0.224
(c) E(X) = np =10*1/4 =2.5
2016-01-05 11:09 am
(a)
P(猜對五題)
=(10C5)(0.25)^5 (1-0.25)^5
=0.05839
(b)
P(猜對至少四題)
=1 - C(10,0)(1/4)º * (3/4)¹º - C(10,1)(1/4)¹ * (3/4)⁹ - C(10,2)(1/4)² * (3/4)⁸ - C(10,3)(1/4)³ * (3/4)⁷
= 0.224
(c) E(X) = np =10*1/4 =2.5
P(猜對五題)
=(10C5)(0.25)^5 (1-0.25)^5
=0.05839
(b)
P(猜對至少四題)
=1 - C(10,0)(1/4)º * (3/4)¹º - C(10,1)(1/4)¹ * (3/4)⁹ - C(10,2)(1/4)² * (3/4)⁸ - C(10,3)(1/4)³ * (3/4)⁷
= 0.224
(c) E(X) = np =10*1/4 =2.5
收錄日期: 2021-04-18 14:08:29
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20151206003603AAHbg4H