def S(v, t, m):
    return v * t + v * v / 20 / m


def main():
    T, mu, L = map(float, input().split())

    l = 0.
    r = 100000. * 3.6
    for _ in range(200):
        if abs(r - l) < 1e-9:
            break
        f = (l + r) * 0.5
        if S(f, T, mu) > L:
            r = f
        else:
            l = f

    ans = str(r * 3.6)
    if "." in ans:
        dot = ans.index(".")
        print(ans[:dot+3])
    else:
        print(ans, "00", sep=".")


T = int(input())
for _ in range(T):
    main()