18/10/15 07:22:39.84 tv/e1MFT.net
f <- function(ratio=1.2,wm=0.2,total=1000,pass=100){
woman=total*wm
man=total-woman
i=0:pass
sum((choose(man,i)*choose(woman,pass-i)/choose(total,pass))*(i/man > ratio*(pass-i)/woman))
}
f()
r=seq(1,3,length=1000)
p=sapply(r,f)
plot(r,p,pch=19,type='n',bty='l',xlab='M/F ratio',ylab='probability')
abline(h=0.01,lty=3)
g <- function(wm) lines(r,sapply(r,function(r)f(r,wm)),col=10*wm,lwd=10*wm)
for(i in 1:5/10) g(i)
legend('center',bty='n',lwd=1:5,col=1:5,
legend=c('10%','20%','30%','40%','50%'))
woman=200
man=800
total=woman+man
pass=100
x=rep(0:1,c(woman,man))
sim <- function(ratio=1.2){
y=sample(x,pass)
M=sum(y)/man
W=(pass-sum(y))/woman
M/W>=ratio
}
re=replicate(1e3,mean(replicate(1e3,sim(1.2))))
f(1.2)