#include <iostream>
#include <stdio.h>
#include <string.h>
using namespace std;

int main()
{

    double pro[110];
    int val[110];
    int t;
    int n;
    int j;
    int cnt;
    double exp;

    scanf("%d", &t);

    for (int cs = 1; cs <= t; cs++)
    {
        scanf("%d", &n);
        memset(pro, 0, sizeof(pro));
        pro[1] = 1;


        for (int i = 1; i <= n; i++)
        {
            scanf("%d", val + i);
            pro[i]=1;
        }

        exp = val[1];

        for (int i = 2; i <= n; i++)
        {

            int k=i+5;
            k=min(k,n);
            cnt=k-i+1;
            for(int j=1; j<=6&&i-1+j<=k; j++)
            {
                int x=i-1+j;
                cnt=max(1,cnt);
                pro[x]=pro[x]*( double(1) / double(cnt));
               // cout<<cnt<<" "<<x<<" "<<pro[x]<<endl;
                exp = exp + pro[x] * val[x];
                cnt--;

            }
            if(k==n) break;
        }
        printf("Case %d: %lf\n", cs, exp);

    }

}