rm(list=ls())

MODE <- function(x) {
dens <- density(x)
mode_i <- which.max(dens$y)
mode_x <- dens$x[mode_i]
mode_y <- dens$y[mode_i]
c(mode=mode_x, value=mode_y)
}

invest <- function(p,q){
win=sample(1:0,1,prob=c(p,1-p))
try=1
while(!win){
win=sample(1:0,1,prob=c(p,1-p))
try=try+1
}
return(try*q)
}
par(mfrow=c(2,1))
k=1e6
re.3=replicate(k,invest(0.30,300))
hist(re.3,freq=FALSE,col='lightblue')
summary(re.3)
MODE(re.3)[1]

re.6=replicate(k,invest(0.60,800))
hist(re.6,freq=FALSE,col='lightblue')
summary(re.6)
MODE(re.6)[1]