#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cmath>
#include<cstdlib>
#include<algorithm>
using namespace std;
int tt,n,a[52];
bool cmp(int x,int y)
{
      return x>y;
}
int main()
{
      scanf("%d",&tt);
      while(tt--)
      {
            scanf("%d",&n);
            for(int i=1;i<=n;i++)
                  scanf("%d",&a[i]);
            sort(a+1,a+1+n,cmp);
            double ans=0;
            for(int i=1;i<=n;i++)
                  ans+=pow(0.95,i-1)*a[i];
            printf("%.10lf\n",ans);
      }
      return 0;
}