Water flows through two different pipes A and B of the same circular cross-section but at different flow rates. The length of pipe A is $1.0 \: m$ and that of pipe B is $2.0 \: m$. The flow in both the pipes is laminar and fully developed. If the frictional head loss across the length of the pipes is same, the ratio of volume flow rates $Q_B/Q_A$ is _____ (round off to two decimal places).