An equimolar binary mixture is to be separated in a simple tray-distillation column. The feed rate is $50\text{ kmol min}^{-1}$ . The mole fractions of the more volatile component in the top and bottom products are $0.90$ and $0.01$, respectively. The feed as well as the reflux stream are saturated liquids. On application of the McCabe-Thiele method, the operating line for the stripping section is obtained as $$y = 1.5x - 0.005$$ where $y$ and $x$ are the mole fractions of the more volatile component in the vapor and liquid phases, respectively. The reflux ratio is __________ (rounded off to two decimal places).