#include<stdlib.h>
#include<stdio.h>

void festival(int **line, int L, int LINENUM);

int main(){
    int CASE, i, j, k, LINENUM, L;
    int **line;

    scanf("%d",&CASE);

    for(i = 0 ; i < CASE ; ++i){
        scanf("%d %d",&LINENUM,&L);
        line = (int**)malloc(sizeof(int*)*LINENUM);

        for(j = 0 ; j < LINENUM ; ++j){
            line[j] = (int*)malloc(sizeof(int)*LINENUM);
            scanf("%d",&line[j][j]);

            for(k = j-1 ; k >= 0 ; --k){
                line[k][j] = line[k][j-1]+line[j][j];
            }
        }

        festival(line,L,LINENUM);
        for(j = 0 ; j < LINENUM ; ++j){
            free(line[j]);
        }
        free(line);
    }

    return 0;
}

void festival(int **line, int L, int LINENUM){
    int i, j;
    float min;
    float temp;

    min = 99999999999;

    for(i = 0 ; i <= L ; ++i){
        for(j = L-1+i ; j < LINENUM ; ++j){
            temp = (float)line[i][j]/(j-i+1);
            if(temp < min){
                min = temp;
            }
        }
    }

    printf("%.11f\n",min);
}