using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static long[] NList => ReadLine().Split().Select(r => long.Parse(r.Replace(".", ""))).ToArray();
    static void Main()
    {
        var t = NN;
        var res = new long[t];
        for (var u = 0; u < t; ++u)
        {
            var c = NList;
            var (T, m, L) = (c[0], c[1], c[2]);
            var ng = 1836001L;
            var ok = 0L;
            while (ng - ok > 1)
            {
                var v = (ok + ng) / 2;
                if (25 * v * v + 18 * m * v * T <= 6480 * m * L) ok = v;
                else ng = v;
            }
            res[u] = ok;
        }
        WriteLine(string.Join("\n", res.Select(r => $"{r / 100}.{r % 100 :00}")));
    }
}