1

I'm repeating this question since they don't seem to like it over there: https://stackoverflow.com/questions/21972403/average-train-speed

This is the question I have:

If a train is traveling at 50 mph for 30 miles and makes 3 stops 15 min apart what is the average mph for the trip? 35 mph 42 mph 26 mph

My question here is, anyone can explain to me this question? I tried all combination of thoughts and never got an answer close to the available options.

If the train is traveling at 50mph for 30 miles then it will take 36 minutes to arrive at its destination, but what it's meant here by 3 stops "15 min" apart?

Is it 15 minutes taken as a rest at each stop (total trip time will be 81 minutes)? Is it 15 minutes travel time till the train stops? then on average 10 miles per 15 minutes and hence the average speed would be 40mph...

The final destination is considered as a stop?

The question for me is too vague, can someone explain it better for me?

Community
  • 1
AMahdy
  • 11
  • The closer imagination of the correct answer I got so far is: departure is a stop, destination is a stop, and there is a middle third stop, total time spend is 36 mins + 15 mins = 51 mins hence avg speed is 35.3 mph .. – AMahdy Feb 23 '14 at 18:50

1 Answers1

1

The problem is not well stated. You don't care the time between stops, just the total time stopped. Add that to the $36$ minutes spent traveling to get the total time.

Ross Millikan
  • 374,822
  • Tried that with all combinations: 3 stops = 45 mins, then total time is 81 mins (speed = 22.2 mph). 2 stops (and the third is the destination?) then total is 66 mins (speed = 27.3 mph). – AMahdy Feb 23 '14 at 18:47
  • The closer imagination of the correct answer I got so far is: departure is a stop, destination is a stop, and there is a middle third stop, total time spend is 36 mins + 15 mins = 51 mins hence avg speed is 35.3 mph .. – AMahdy Feb 23 '14 at 18:52
  • I think you clearly understand the concept of the question. I still believe there isn't enough information, so am not surprised you are confused. – Ross Millikan Feb 24 '14 at 00:31