# include <iostream>

 # include <cstdio>

 # include <algorithm>

 # include <map>

 # include <cmath>

 # define LL long long

 using namespace std ;

 int a[] ;

 bool cmp (int x , int y)

 {

     return x > y ;

 }

 int main ()

 {

     int T ;

     scanf("%d" , &T) ;

     while(T--)

     {

         int n ;

         scanf("%d" , &n) ;

         int i ;

         for (i =  ; i<=n ;i++)

             scanf("%d" , &a[i]) ;

         sort(a+,a++n,cmp) ;

         double sum =  ;

         for (i =  ; i<=n ;i++)

         {

             sum+=(pow(0.95,i-)*a[i]) ;

         }

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

     }

     return  ;

 }