Question

On a 120 km track, a train travels the first 30 km at a uniform speed of 30 km/hr. How fast must the train travel in the next 90 km so that the average velocity for the entire trip is 60 km/hr?

Answer 1

speed of the train in the first 30 km ,v1=30km/h
speed of the train in the next 90km ,v2=?average speed                                    =(v1+v2)/2                                                              = 30+v2/2         
 v2=90km/h

Answer 2

Hy Mate
Speed of the train in the first 30 km, 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

so I hope it will help you
thank you ❤