#include <bits/stdc++.h>
using namespace std;
 
int main()
{
    int t;
    cin>>t;
 
    for(int z=0;z<t;z++)
    {
        int n;
        cin>>n;
 
        double a[n];
        //priority_queue<double,vector<double> > pq;
        priority_queue<double> pq;
 
        for(int i=0;i<n;i++)
        {
            double x;
            cin>>x;
            pq.push(x);
        }
 
        while(pq.size()!=1)
        {
            double x = pq.top();
           pq.pop();
            double y = pq.top();
           pq.pop();
           pq.push((x+y)/2);
        }
 
        //cout<<pq.top()<<"\n";
        printf("%.10f\n",pq.top());
        //cout<<setprecision(10)<<pq.top()<<"\n";
    }
    return 0;
}

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