# require "debug"
alias LL = Int64
macro chmin(x, y); {{x}} = {{y}} if {{x}} > {{y}}; end
macro chmax(x, y); {{x}} = {{y}} if {{x}} < {{y}}; end
macro yn(x); {{x}} ? "Yes" : "No"; end

# ---------------------------------------------------- :)

def f(t,u,v)
  return v*t + (v*v)/(u*20)
end

read_line.to_i.times do
  t, u, l = read_line.split.map(&.to_f)
  ng = 0
  ok = 1000000000
  while ok-ng > 0.002
    mid = (ok+ng)/2
    if f(t,u,mid) <= l
      ng = mid
    else
      ok = mid
    end
  end
  printf("%.2f\n", (ng*3600)/1000 )
end