Find the equivalent single pipe 1000 m in length to replace three parallel pipes as illu...

Find the equivalent single pipe 1000 m in length to replace three parallel pipes as illustrated in Figure 4-41 if the pipes between A and B are as follows: upper pipe 1800 m in length and 150 mm in diameter, center pipe 1000 m and 200 mm, and bottom pipe 1400 m and 250 mm.