#include <iostream>

using namespace std;

int main() {
    int C;
    cin >> C;

    while( C-- ) {
        int N, L;
        cin >> N >> L;
        int *price = new int[N];
        for( int i=0; i<N; i++ ) {
            cin >> price[i];
        }

        double min = 1000000;
        for( int distance=N; distance>=L; distance-- ) {
            for( int i=0; i<N; i++ ) {
                if( i+distance <= N ) {
                    double avg = 0;
                    for( int j=i; j<i+distance; j++ ) {
                        avg += price[j];
                    }
                    avg /= distance;
                    if( avg < min ) {
                        min = avg;
                    }
                }
            }
        }


        cout << fixed;
        cout.precision( 7 );
        cout << min << endl;
    }
}