#nullable enable

#region
var (_input, _iter) = (Array.Empty<string>(), 0);
T I<T>() where T : IParsable<T>
{
    while (_iter >= _input.Length) (_input, _iter) = (Console.ReadLine()!.Trim().Split(' '), 0);
    return T.Parse(_input[_iter++], null);
}
#endregion

static double F(long k, int n, int m)
{
    var t = (k + m - 1) / m;
    var s = (long)n * m;
    var r = 1.0 - ((double)t) / s;
    if (t == n)
    {
        double l = k - s + m - 1;
        r *= 1.0 - l / (m - 1);
    }
    return r;
}

var t = I<int>();
var ans = new List<string>();
while (t-- > 0)
{
    var n = I<int>();
    var m = I<int>();
    var k = I<long>();
    var p = F(k, n, m);
    ans.Add(p.ToString("F14"));
}
Console.WriteLine(string.Join(Environment.NewLine, ans));