word problem

[sud21]

A person travelled from X to Y and arrived at Z. If the average speed in the whole trip is 15feet/second, what is the average speed during the route from Y to Z?
1) The average speed from X to Y is 10 feet per second
2) It took 20 seconds from Y to Z

[MBACenter]

A person travelled from X to Y and arrived at Z. If the average speed in the whole trip is 15feet/second, what is the average speed during the route from Y to Z?
1) The average speed from X to Y is 10 feet per second
2) It took 20 seconds from Y to Z

Again, it's not clear what the problem is asking! Is Z in between X and Y or is Y between X and Z? What was the original answer? That would help shed some light on what the authors meant to ask.