#include<iostream>

#include<cstdio>

#include<cmath>

#include<cstdlib>

#include<cstring>

#include<algorithm>

using namespace std;

#define ll long long

char getc(){char c=getchar();while ((c<'A'||c>'Z')&&(c<'a'||c>'z')&&(c<''||c>'')) c=getchar();return c;}

int gcd(int n,int m){return m==?n:gcd(m,n%m);}

int read()

{

    int x=,f=;char c=getchar();

    while (c<''||c>'') {if (c=='-') f=-;c=getchar();}

    while (c>=''&&c<='') x=(x<<)+(x<<)+(c^),c=getchar();

    return x*f;

}

double f[][][][];

int T,n,a,b,c;

int main()

{

#ifndef ONLINE_JUDGE

    freopen("bzoj4832.in","r",stdin);

    freopen("bzoj4832.out","w",stdout);

    const char LL[]="%I64d\n";

#else

    const char LL[]="%lld\n";

#endif

    T=read();

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

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

            for (int y=;y<=-x;y++)

                for (int z=;z<=-x-y;z++)

                {

                    f[i][x][y][z]=f[i-][x][y][z]+;

                    if (x) f[i][x][y][z]+=f[i-][x-][y][z]*x;

                    if (y) f[i][x][y][z]+=f[i-][x+][y-][z+(x+y+z<)]*y;

                    if (z) f[i][x][y][z]+=f[i-][x][y+][z-+(x+y+z<)]*z;

                    f[i][x][y][z]/=(x+y+z+);

                }

    while (T--)

    {

        n=read(),a=read(),b=read(),c=read();

        printf("%.2lf\n",f[n][a][b][c]);

    }

    return ;

}