#include <iostream>
#include <cstdio>
#include <cmath>
#include <climits>

using namespace std;

double logN[1001];
double factN[1001];

double fact(int n)
{
    if(n == 0)
    {
        return 0;
    }

    if(factN[n - 1] != 0)
    {
         factN[n] = logN[n] + factN[n - 1];
    }
    else
    {
        factN[n] = logN[n] + fact(n - 1);
    }

    return factN[n];
}

int main()
{
    int nCase;
    cin >> nCase;

    for(int i = 1; i <= 1000; i++)
    {
        logN[i] = log(i);
    }

    double log25 = log(0.25);
    double log3 = log(3);
    while(nCase--)
    {
        int n, m;
        cin >> n >> m;

        int d = n - m;
        if(d < 0)
        {
            printf("%.10f\n", 1.);
            continue;
        }

        double prSum = 0;
        double factM = fact(m);

        for(int i = d; i <= m; i++)
        {
            double t = factM - fact(m - i) - fact(i);
            prSum += exp(t + log3 * i + log25 * m);
        }

        printf("%.10f\n", prSum);
    }
    return 0;
}