groupPerformance

public static void groupPerformance(){
        System.out.println ("***************************************\n"+
                    "What would you like to know?\n"+
                    "1.- Group average \n"+
                    "2.- Group Variance \n"+
                    "3.- Group Standard Deviation \n"+
                    "4.- Number of students that passed and number of stufents that failed. \n"+
                    "***************************************\n");

        int option =sc.nextInt();
        int[] grade= new int [20];
        for(int i=1; i<21;i++)
            grade[i-1]=Integer.parseInt(finalGrade(i));
        int sum=0;
        int numberGrades=0;
        int groupaverage=-1;
        int sumvariance = 0;
        int variance = 0;

        for(int i=0;i<20;i++){
             if(grade[i]!= 0 ){
                 sum += grade[i];
                 numberGrades++;
             }
        }
        if(numberGrades!=0){
            groupaverage = sum/numberGrades;
        }

        for(int i=0;i<20;i++){
            if(grade[i]!= 0){
                sumvariance += (int) Math.pow((grade[i]-groupaverage),2);
            }
        }

        if(numberGrades!=0){
            variance = sumvariance/numberGrades;
        }
        int dev=(int)Math.sqrt(variance);

        switch(option){
            case 1:
                System.out.println("The group Average is: " + groupaverage);
                break;
            case 2:
                System.out.println("The group Variance is: "+ variance);
                break;
            case 3:
                System.out.println("The group Standard Deviation is: "+ dev);
                break;

            case 4:
                int p=0;
                int f=0;
                for(int i=0;i<20;i++){
                    if(grade[i]!= 0 & grade[i]<70){
                        f++;
                    }
                    if(grade[i]!= 0 & grade[i]>=70){
                        p++;
                    }
                }
                System.out.println("Number of students that passed: " + p + "\nNumber of students that failed: " + f);
                break;
        }
    }