#include <stdio.h>

void sort(double base[], int n);

int main()
{
    int testCase, i, j;
    int studentCount;
    double score[41]; 
    double mid; 

    scanf("%d", &testCase);

    while(testCase--) 
    {
        scanf("%d", &studentCount);

        for(i = 0; i < studentCount; i++)
            scanf("%lf", &score[i]);

        sort(score, studentCount);

        int start = 0, end = studentCount - 1;
        double mid, sum_Avg[studentCount];

        if(studentCount % 2 != 0)
        {
            mid = score[studentCount / 2];

            for(i = 0; i < studentCount / 2; i++)
            {
                sum_Avg[i] = (score[start++] + score[end--]) / 2;

                if(start == end)
                {
                    sum_Avg[i + 1] = mid;
                    break;
                }
            }
        }
        else
        {
            for(i = 0; i < studentCount / 2; i++)
            {
                sum_Avg[i] = (score[start++] + score[end--]) / 2;

                if(start == end)
                    break;
            }   
        }
        double result = 0;

        for(i = 0; i < sizeof(sum_Avg) / sizeof(sum_Avg[0]); i++)
        {
            if(result <= sum_Avg[i])
                result = sum_Avg[i];
        }

        printf("%.1lf\n", result);
    }
}

void sort(double base[], int n)
{
    int i, j;
    double temp;

    for(i = 0; i < n; i++)
    {
        for(j = i; j < n; j++)
        {
            if(base[i] > base[j])
            {
                temp = base[i];
                base[i] = base[j];
                base[j] = temp; 
            }   
        }   
    }
}