#int(input())
#map(int, input().split())
#list(map(int, input().split()))

N = int(input())

T = [0] * N
for i in range(N):
    T[i] = list(map(float, input().split()))
#     T[i] = input().split()

# for i in range(N):
#     for j in range(3):
#         s = T[i][j]
#         T[i][j] = int(s[:-3]) * 100 + int(s[-2:]) * 1

def S(v, t, m):
    v *= 1000 / 3600
    return v * t + v * v / 20 / m

# print(T)

for i in range(N):
    t = T[i][0]
    m = T[i][1]
    l = T[i][2]

    vmax = 5200
    vmin = 0

    while vmax - vmin > 0.001:
        h = (vmax + vmin) / 2
        if S(h, t, m) > l:
            vmax = h
        else:
            vmin = h

    print(format(int(vmin*100)/100, ".2f"))


#     # print(vmin)

#     a, b = divmod(vmin, 10)
#     c, d = divmod(a, 100)
#     print(str(c) + "." + format(d, "02d"))