import std;

void main() {
    int N;
    readf("%d\n", N);

    real MAX = 6000.0, EPS = 1e-10;

    real S(real v, real t, real m) {
        real u = v / 3.6;
        return u * t + u * u / (20.0 * m);
    }

    foreach (_; 0 .. N) {
        real T, mu, L;
        readf("%f %f %f\n", T, mu, L);

        real ok = 0.0, ng = MAX;
        while (ng - ok > EPS) {
            real mid = (ok + ng) / 2.0;

            real l = S(mid, T, mu);
            (l < L ? ok : ng) = mid;
        }

        auto tmp = format("%.10f", ok);
        dchar[] res;
        int cnt = -100;
        foreach (t; tmp) {
            if (cnt >= 2) break;

            res ~= t;
            if (t == '.') cnt = 0;
            else ++cnt;
        }

        res.writeln;
    }
}