import sys
input = sys.stdin.readline

N=int(input())
for _ in range(N):
    T,m,L=map(float,input().split())
    b=20*m*T
    c = -20*m*L
    ans = (b**2-4*c)**0.5 - b
    ans /= 2
    ans *= 3600/1000 * 100
    ans = int(ans)
    print(f"{ans/100:.2f}")