package festival;

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Festival {
static int caseNum;
static int N, L;
static int timeArr[];

public static void main(String args[]) throws Exception {
    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
    caseNum = Integer.parseInt(bufferedReader.readLine());

    for (int i = 1; i <= caseNum; i++) {
        String inputStr[] = bufferedReader.readLine().split(" ");
        N = Integer.parseInt(inputStr[0]);
        L = Integer.parseInt(inputStr[1]);

        timeArr = new int[N + 1];
        inputStr = bufferedReader.readLine().split(" ");
        for (int j = 1; j <= N; j++) {
            timeArr[j] = Integer.parseInt(inputStr[j - 1]);
        }
        double min = Double.MAX_VALUE;
        double result = 0;

        //L==N 바로 return
        if (L == N) {
            for (int n : timeArr) {
                result += n;
            }
            min = result / L;
            System.out.printf("%.12f", min);
            return;
        }


        for (int j = L; j <= N; j++) {
            for (int k = 1; k <= N; k++) {
                result = 0;
                for (int o = 0; o < j; o++) {
                    if (k + j <= N+1) {
                        result += timeArr[k + o];
                    }
                }
                result = result / j;
                if (min > result && result != 0) {
                    min = result;
                }
            }
        }
        System.out.printf("%.12f\n", min);
    }
}

}