A sales manager receives 6 telephone calls on average between 9 : 30am and 10 : 30am on a weekday. Find the probability that
(a) he will receive 2 or more calls between 9 : 30am and 10 : 30am on a certain weekday
(b) he will receive exactly 2 calls between 9 : 30am and 9 : 40am;
(c) during a normal 5-day working week, there will be exactly 3 days on which he will receive no calls between 9 : 30am and 9 : 40am.
probability?
2015-11-18 6:26 am
回答 (1)
2015-11-18 10:59 am
✔ 最佳答案
(a)λ = 6
P(x) = λ^x * e^(-λ) / x ! = 6^x * e^(-6) / x !
P( x ≧ 2 )
= 1 - P(0) - P(1)
= 1 - 6^0*e^(-6)/0! - 6^1*e^(-6)/1!
= 1 - e^(-6) - 6*e^(-6)
= 1 - 7*e^(-6)
≒ 0.9997
(b)
λ = 6*(10/60) = 1
P(2)
= 1^2 * e^(-1) / 2 !
= (1/2)*e^(-1)
≒ 0.1839
(c)
λ = 1
C(5,3) * P(0)^3
= 10 * [ 1^0 * e^(-1) / 0 ! ]^3
= 10*e^(-3)
≒ 0.4979
Ans:
(a) 1 - 7*e^(-6) ( ≒ 0.9997 )
(b) (1/2)*e^(-1) ( ≒ 0.1839 )
(c) 10*e^(-3) ( ≒ 0.4979 )
收錄日期: 2021-04-24 23:37:31
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20151117222636AAUB97b