ATQ, Let, length of train Q = ‘p’ m Speed of train Q = p/16.8 Let, speed of train P = ‘q’ m/s So, (p + 730)/(p/16.8) = 46 16.8p + 12264 = 46p p = 420 Speed of train Q = 420/16.8 = 25 m/s So, (300 + 420)/(25 + q) = 16 720 = 400 + 16q q = 20 m/s Required time = (730 + 300)/20 = 51.5 seconds