Train 1 travelling at a speed of 80 km/hr leaves station A at 6:00 a.m., and train 2 travelling at 105 km/hr starts from station A at 8:30 a.m. in the same direction on a parallel track. At what distance (in km) from station A will train 2 meet train 1?
840
Train 1 leaves at 6:00 a.m., and Train 2 leaves at 8:30 a.m. So, Train 1 has a 2.5-hour head start. In that time, Train 1 travels: 80 km/hr × 2.5 hrs = 200 km. The relative speed of Train 2 to Train 1 is (105 - 80) = 25 km/hr. Now, Train 2 needs to cover the 200 km gap at a speed of 25 km/hr. Time taken = 200 km ÷ 25 km/hr = 8 hours. Thus, the distance at which they meet is: Train 2's speed × time = 105 km/hr × 8 hrs = 840 km.
Rishi travels 198 km at 66 km/hr, the next 584 km at 73 km/hr and the next 656 km at 82 km/hr. What is his average speed (in km/hr) for the whole journey? (Round off your answer to two decimal places)