54.5 km/h . First part = 50 / 50 = 60 minutes Second part = 50 / 60 = 50 minutes Total time = 110 minutes. Total distance = 100 km Average speed = 100 / (110/60) =54.5 km/hr

Ram travels a certain distance at 3km/hr and reached 15 min late. If he travels at 4 km/hr, he reached 15 min earlier. What is the distance he has to travel.

Two trains each 333 meter long, are running in opposite directions on parallel tracks. If their speeds are 45 km/hr and 66 km/hr respectively, then what is the time taken by the faster train to pass the driver of slower one?