Two capillary tubes A and B of equal radii r a = r b = r and equal lengths  a =  b = …

Two capillary tubes A and B of equal radii r_a = r_b = r and equal lengths _a = _b =  are held horizontally. When the same pressure difference P is maintained across each tube, the rate of flow of water in each is Q. If the tubes are connected in series and the same pressure difference P is maintained across the combination, the rate of flow through the combination will be