#include <stdio.h>
#include <string.h>

int main()
{
    //input

    int count;
    int cost[1100];
    int cost1;
    int min;
    int max;
    double out;
    double in;
    double result;
    int i = 0, j = 0;
    scanf("%d", &count);
    if (count <= 100 && count >= 0)
    {
        for (i = 1; i <= count; i++)
        {
            out = 101;
            result = 0;
            in = 0;

            scanf("%d %d", &max, &min);
            if (max >= min&&max <= 1000 && min >= 1) {



                for (j = 1; j <= max; j++)
                {
                    scanf("%d", &cost1);
                    if (cost1 <= 100 && cost1 >= 0) {
                        cost[j] = cost1;

                        in = in + (double)cost[j];
                        if (j >= min)
                        {
                            result = in / (j);
                            if (result < out)
                                out = result;
                        }
                    }
                }
                memset(cost, 0, sizeof(int)*max);
                max = 0;
                min = 0;
                cost1=0;

            }
            printf("%.10lf\n", out);
        }
    }

    return 0;
}