n*****t
发帖数: 834 | 1 看不懂题
A company takes out an insurance policy to cover accidents that occur at its
manufacturing plant. The probability that one or more accidents will occur
during any given month is 3/5. The number of accidents that occur in any
given month is independent of the number of accidents that occur in all
other months.
Calculate the probability that there will be at least four months in which
no accidents occur before the fourth month in which at least one accident
occurs.
就是最后那句话读不明白
谢谢 |
n*****t
发帖数: 834 | |
w**k
发帖数: 112 | 3 标准的binomial distribution with r=4 |
n*****t
发帖数: 834 | 4 好像不是的，后面查到答案的解释了，应该是negative binomial distribution.
【在 w**k 的大作中提到】
: 标准的binomial distribution with r=4
|
b********s
发帖数: 152 | 5 看你伪币不少，帮你回答一下,请转20伪币
家页-> 金融中心->银行(新伪币)转帐->帐号(blessuscis)->金额(20)
这是一个 negative binomial distribution (X) with r=4,p=0.6
X:当第四个有事故发生月份时，没有事故的月份数。就是让你求P[X>=4]
你可以求1-P[x=1,x=2,x=3]
P[X=0]=前四个月都有事故发生 (0.6)^4
P[X=1]=前四个月一个月没有事故发生，3个月有事故发生，第5个月有事故发生（第四
个有事故发生月份）4*（0.4)*(0.6)^3*(0.6)
同理 p[X=2]=10*(0.4)^2*(0.6)^3(0.6)
p[X=3]=20*(0.4)^3*(0.6)^3(0.6) |
