I slapped together some C++ in under ten minutes, with an eye towards making it run fast. This runs a billion iterations in slightly under one minute on my machine.

#include <cstdlib>
#include <ctime>
#include <iostream>
using namespace std;
long long threshhold = 4 * (RAND_MAX / 9);
int main() {
srand((unsigned)time(0));
long long utility = 0;
long long iterations = 1000000000;
for(long long i = 0; i < iterations; ++i) {
if(rand() < threshhold)
continue;
else if(rand() < threshhold) {
utility += 4;
continue;
}
++utility;
}
cout << "avg utility: " << (double)utility/iterations << endl;
return 0;
}