The rate of flow of a certain liquid of viscocity through a...

The rate of flow of a certain liquid of viscocity $\eta$ through a horizontal capillary of length $l$ and radius $r$ is $Q$ when the pressure head at the inlet is just twice the atmospheric pressure. The rate of flow of the same liquid through another capillary of length $2 l$ and radius $2 r$ when the inlet pressure head is 4 times the atmospheric pressure will be (The outlet being open to atmosphere in each case)