#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
int main() 
{
    int ca,day,team;
    int i,j,k,z,cnt=0;
    int *pay;
    int sum=0;
    double avg=0;
    double min = INT_MAX;
    double *ary;
    scanf("%d",&ca);
    ary = (double *)malloc(sizeof(double)*ca);
    for(i=0;i<ca;i++) {
        scanf("%d %d",&day, &team);
        pay = (int *)malloc(sizeof(int)*day);
        for(j=0;j<day;j++) {
            scanf("%d",&pay[j]);
        }
        for(j=0;j<day;j++) {
            for(k=team+j;k<day;k++) {
                for(z=j;z<k;z++) {
                    sum += pay[z];
                }
                avg = (double)sum/(k-j);
                if(min > avg) {
                    min = avg;
                }

                sum = 0;
            }
        }
        ary[cnt++] = min;
    }

    for(i=0;i<ca;i++) {
        printf("%.10lf\n",ary[i]);
    }
    return 0;
}