#include <iostream>
using namespace std;

double avg(int start, int end, int *cost) {

    double sum = 0.0;
    double avg = 0.0;
    for (int i = start; i <= end; i++) {
        sum += cost[i];
    }
    avg = sum / (end - start + 1);
    return avg;

}

double festival(int N, int L, int *cost) {

    double currentcost = 0.0;
    double mincost = 999999999999999999999999999999.0;
    for (int i = L; i < N + 1; i++) {
        for (int j = 0; j < N - i + 1; j++) {
            currentcost = avg(j, j + i - 1, cost);
            if (mincost > currentcost)  mincost = currentcost;
        }
    }

    return mincost;

}

int main(void) {
    int num;
    int N, L;

    cin >> num; //반복 횟수
    for (int i = 0; i < num; i++) {
        cin >> N;
        cin >> L;
        int *cost = new int[N]; //대여비용을 담을 배열
        for (int i = 0; i < N; i++) {
            cin >> cost[i];
        }
        double avgcost = festival(N, L, cost);
        cout.setf(ios::fixed);

        cout.precision(11);
        cout << showpoint << avgcost << endl;
        delete cost;
    }

    return 0;
}