code: public class Bias {
      public static boolean biased(int n) {
          return Math.random() < 1.0 / n;
      }
  
      public static boolean unbiased(int n) {
          boolean a, b;
          do {
              a = biased(n);
              b = biased(n);
          } while (a == b);
          return a;
      }
  
      public static void main(String[] args) {
          final int M = 50000;
          for (int n = 3; n < 7; n++) {
              int c1 = 0, c2 = 0;
              for (int i = 0; i < M; i++) {
                  c1 += biased(n) ? 1 : 0;
                  c2 += unbiased(n) ? 1 : 0;
              }
              System.out.format("%d: %2.2f%%  %2.2f%%\n",
                                n, 100.0*c1/M, 100.0*c2/M);
          }
      }
  }
  