#include <iostream>
#include <algorithm>
using namespace std;
const double INF=1e18;
int n;
int a[300010];
double s[300010];
bool check(double mid){
	for(int i=1;i<=n;i++)
		s[i]=s[i-1]+(double)a[i]-mid;
	double mi=INF;
	for(int i=1;i<n;i++){
		if(a[i]>a[i+1]) mi=min(mi,s[i-1]);
		else if(a[i]==a[i+1]) mi=INF;
		else if(mi!=INF){
			int j=i+1;
			while(j<=n && a[j]>a[j-1]){
				if(s[j++]-mi>=0) return true;
			}
			mi=INF;
			i=j-2;
		}
	}
	return false;
}
signed main(){
	int t;
	scanf("%d",&t);
	while(t--){
		scanf("%d",&n);
		for(int i=1;i<=n;i++) scanf("%d",&a[i]);
		double l=0,r=1e9;
		while(r-l>1e-9){
			double mid=(l+r)/2;
			if(check(mid)) l=mid;
			else r=mid;
		}
		printf("%.18lf\n",r);
	}
	return 0;
}