#pragma comment(linker, "/STACK:1024000000,1024000000")

#include<cstdio>

#include<cstring>

#include<cmath>

#include<algorithm>

#include<vector>

#include<map>

#include<set>

#include<queue>

#include<stack>

#include<iostream>

using namespace std;

typedef long long LL;

const double pi=acos(-1.0),eps=1e-;

void File()

{

    freopen("D:\\in.txt","r",stdin);

    freopen("D:\\out.txt","w",stdout);

}

template <class T>

inline void read(T &x)

{

    char c = getchar();

    x = ;

    while(!isdigit(c)) c = getchar();

    while(isdigit(c)) { x = x *  + c - ''; c = getchar(); }

}

int a[],T,n;

double ans[];

int main()

{

    scanf("%d",&T); int cas=;

    while(T--)

    {

        scanf("%d",&n);

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

        {

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

            ans[i]=1.0*a[i];

        }

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

        {

            int cnt=; double sum=;

            for(int j=;j<=;j++)

            {

                if(i+j>n) break;

                cnt++; sum=sum+ans[i+j];

            }

            ans[i]=ans[i]+sum/cnt;

        }

        printf("Case %d: %lf\n",cas++,ans[]);

    }

    return ;

}