#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 decimal F(long k, int n, int m)
{
    // if (k <= 0) return 1;
    // var res = F(k - m, n - 1, m) * (n - 1) / n + (double)(m - 1) / (n * m);
    // return res;
    decimal t = (k + m - 1) / m;
    return (t * (m - 1) / m + n - t) / n;
}

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));