n = int(input())
for _ in range(n):
    t, mu, l = map(float, input().split())
    left = 0.0
    right = 5200.0
    for _ in range(60):
        mid = (left + right) / 2
        v = 5 * mid / 18
        d = v * t + v**2 / (20 * mu)
        if d < l:
            left = mid
        else:
            right = mid
    right *= 100
    right = int(right)
    print(f"{right/100:.2f}")