Question

9) a train travels the first 30 km of 120 km track with a uniform speed of 30 km h-1. what should be the speed of the train to cover the remaining distance of the track so that its average speed is 60 km h-1 for the entire trip ?

Answer 1

90 km/h will be the answer of this question

Answer 2

                           ANSWER                            

                          In the first 30 km speed of the train, v1 = 30 km/h

                          Speed of the train in the next 90 km, v2 (to be determined)

                         Average speed = 60 km/h = (v1 + v2)/2  

                                         = (30 km/h + v2)/2  

                              → v2 = 90 km/h