def solve():
    t, m, L = map(float, input().split())
    t = int(100 * t + 0.0001)
    m = int(100 * m + 0.0001)
    L = int(100 * L + 0.0001)
    l = 0
    r = 510001
    
    f = lambda x:18*m*x*t + 25*x*x <= 18*18*20*m*L


    while r - l > 1:
        mid = (l + r) // 2
        if f(mid):
            l = mid
        else:
            r = mid

    a = l // 100
    b = l - 100 * a
    ans = "{}.{:0>2}".format(a, b)
    print(ans)

for _ in range(int(input())):
    solve()