n <- 10^7 # numero di lanci da simulare
sum(replicate(n, sum(sum(sample(0:1, 3, replace = TRUE) ) >= 2) ) )/n
sum(replicate(n, sum(sum(sample(0:1, 30, replace = TRUE) ) >= 20) ) )/n
sum(replicate(n, sum(sum(sample(0:1, 300, replace = TRUE) ) >= 200) ) )/n

# Output
> n <- 10^7 # numero di lanci da simulare
> sum(replicate(n, sum(sum(sample(0:1, 3, replace = TRUE) ) >= 2) ) )/n
[1] 0.5001478
> sum(replicate(n, sum(sum(sample(0:1, 30, replace = TRUE) ) >= 20) ) )/n
[1] 0.0494758
> sum(replicate(n, sum(sum(sample(0:1, 300, replace = TRUE) ) >= 200) ) )/n
[1] 0