import java.util.ArrayList;

public class Variance {

    public static int sum(ArrayList<Integer> list) {
        int sum = 0;
        for (int number : list) {
            sum += number;
        }
        return sum;
    }

    public static double average(ArrayList<Integer> list) {

        return (double)sum(list) / list.size();
    }

    public static double variance(ArrayList<Integer> list) {
        double variance = 0;
        double difference = 0;
        double square = 0;
            for (double number : list) {
                difference += (average(list) - number);
                square += Math.pow(difference, list.size()) / list.size();
            }

            return square;
    }

    public static void main(String[] args) {
        ArrayList<Integer> list = new ArrayList<Integer>();
        list.add(3);
        list.add(2);
        list.add(7);
        list.add(2);

        System.out.println("The variance is: " + variance(list));
    }

}