n=int(input())
for _ in range(n):
  t,m,l=map(float,input().split())
  ok=0
  ng=2000
  for __ in range(100):
    v=(ok+ng)/2
    if v*t+(v**2)/(20*m)<=l:
      ok=v
    else:
      ng=v
  v=ok
  v=v*3600/1000
  v=int(v*100)
  v=str(v).zfill(6)
  v1,v2=v[:4],v[4:]
  print(str(int(v1))+"."+v2.zfill(2))