Simple constant velocity question

[cherryrocket]

7. Q: "If you must average 60 km/h for a 90 km trip, and you only average 40 km/h for the first 40 km, what velocity must you average the rest of the way?"

A:

90 km 60km/h 1.5h
d v t

1st
40 km 40 km/s 1h
d v t

2nd
50 km ? 0.5h (1.5-1h = 0.5h)
d v t

v = d/t = 50km/0.5h = 100 km/h

Is this the right answer and is it the right way of solving it?

 

[learningphysics]

Yes, looks right to me.