#include<cstdio>

 #include<algorithm>

 using namespace std;

 int a[];

 int main(){

     int t,n;

     while(~scanf("%d",&t)){

         while(t--){

             scanf("%d",&n);

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

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

             }

             sort(a,a+n);

             double ans=,mul=;

             for(int i=n-;i>=;i--){

                 ans+=a[i]*mul;

                 mul*=0.95;

             }

             printf("%.10f\n",ans);

         }

     }

     return ;

 }