Distance between Delhi and Agra is 200km. atrain travels the first 100km at the speed of 50km/h. how fast must the train travel next 100 km so as to average 70km/h for the whole journey?
Time taken to travel first half distance = 100/ 50 = 2 hrs
Time taken to travel second half distance = 100/v
Average speed = 200/ (2 + 100/v)
70 = 200/ (2 + 100/v)
2 + 100/v = 20/7
100/v = 20/7 - 2 = 6/7
v = 100 × 7/6 Km/h
v = 700/6 km/h