The distance between Delhi and Agra is 200 km. A train travels the first 100 km at a speed of 50 km/h. How fast must the train travel the next 100 km, so as to average 70 km/h for the whole journey ?
a) A train travels a distance with a speed of 40 km/h and returns with a speed of 60 km/h. Calculate the average speed of the train.
b) On a 60 km track, a train travels the first 30 km at a uniform speed of 30 km/h. How fast must a train travel the next 30 km so that the average speed is 40 km/hr for the entire trip?