code: public static double pbarVariance(double pbar, int sampleN, int populationN) {
          if(populationN<=0 || sampleN<=0 || sampleN>populationN) {
              throw new IllegalArgumentException("All the parameters must be positive and sampleN smaller than populationN.");
          }
          double f = (double)sampleN/populationN;
          double pbarVariance=((1.0 - f)*pbar*(1.0 - pbar))/(sampleN-1.0);
          
          return pbarVariance;
      }
docs: Calculates Variance for Pbar for a finite population size
  
  @param pbar
  @param sampleN
  @param populationN
  @return