trainA_passengers = c()

for (i in (1:10000)) {
  passengers <- sum(sample(c(0,1),size=1000, replace=TRUE))
  trainA_passengers <- c(trainA_passengers, passengers)
}
hist(trainA_passengers)

enough_seats <- ifelse(trainA_passengers <= 537, 1, 0)
sum(enough_seats) / 10000
## [1] 0.9915