import java.util.*;
public class Main {


    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();

        for (int i=0; i<n; i++) {
            int days = sc.nextInt();
            int team = sc.nextInt();
            int[] price = new int[days];
            for (int j=0; j<days; j++) {
                price[j] = sc.nextInt();
            }
            double sum = 0.0;
            double avg = 0.0;

            double minAvg = 0;
            double recentSlideSum = 0;
            int begin = 0;
            for (int k=0; k<team; k++) {
                sum+=price[k];
            }
            begin = 0;

            avg = sum/team;
            recentSlideSum = sum;
            minAvg = avg;

            for (int k=team; k<days; k++) {
                recentSlideSum -= price[k-team];
                recentSlideSum += price[k];
                double recentAvg = recentSlideSum/team;

                sum += price[k];
                avg = sum / (k-begin+1);
                if (avg < recentAvg) {

                } else {
                    begin=k-team+1;
                    avg = recentAvg;
                    sum = recentSlideSum;
                }

                if (avg < minAvg) minAvg = avg;


            }
            System.out.format("%.11f%n", minAvg); 
        }
    }
}