At what speed was a train traveling on a trip when it had : GMAT Data Sufficiency (DS)
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 20 Jan 2017, 22:02

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# At what speed was a train traveling on a trip when it had

Author Message
TAGS:

### Hide Tags

Manager
Joined: 02 Dec 2012
Posts: 178
Followers: 5

Kudos [?]: 2327 [0], given: 0

At what speed was a train traveling on a trip when it had [#permalink]

### Show Tags

13 Dec 2012, 04:52
14
This post was
BOOKMARKED
00:00

Difficulty:

15% (low)

Question Stats:

71% (01:40) correct 29% (00:58) wrong based on 923 sessions

### HideShow timer Statistics

At what speed was a train traveling on a trip when it had completed half of the total distance of the trip?

(1) The trip was 460 miles long and took 4 hours to complete.
(2) The train traveled at an average rate of 115 miles per hour on the trip.
[Reveal] Spoiler: OA

Last edited by Bunuel on 21 Jul 2013, 10:32, edited 1 time in total.
Edited the OA.
Math Expert
Joined: 02 Sep 2009
Posts: 36583
Followers: 7087

Kudos [?]: 93289 [3] , given: 10555

Re: At what speed was a train traveling on a trip when it had [#permalink]

### Show Tags

13 Dec 2012, 04:58
3
KUDOS
Expert's post
4
This post was
BOOKMARKED
At what speed was a train traveling on a trip when it had completed half of the total distance of the trip?

Notice that we are not told that the train travels at a constant speed.

(1) The trip was 460 miles long and took 4 hours to complete --> the average speed of the train was 460/4=115 miles per hour, but we don't know what was the speed of the train when it had completed half of the total distance (230 miles). Not sufficient.

(2) The train traveled at an average rate of 115 miles per hour on the trip. The same as above. Not sufficient.

(1)+(2) We only know that the average speed of the train was 115 miles per hour, which is not enough to determine the speed of the train when it had completed half of the total distance (230 miles). Not sufficient.

_________________
Intern
Joined: 06 Sep 2012
Posts: 42
Concentration: Social Entrepreneurship
Followers: 0

Kudos [?]: 42 [0], given: 42

Re: At what speed was a train traveling on a trip when it had [#permalink]

### Show Tags

17 Dec 2012, 10:57
why is the official answer D?
_________________

Life begins at the edge of your comfort zone.

Appreciate the +1!

Senior Manager
Status: Prevent and prepare. Not repent and repair!!
Joined: 13 Feb 2010
Posts: 274
Location: India
Concentration: Technology, General Management
GPA: 3.75
WE: Sales (Telecommunications)
Followers: 9

Kudos [?]: 89 [0], given: 282

Re: At what speed was a train traveling on a trip when it had [#permalink]

### Show Tags

25 Dec 2012, 04:20
The OA is E. It is given in the OG as well
_________________

I've failed over and over and over again in my life and that is why I succeed--Michael Jordan
Kudos drives a person to better himself every single time. So Pls give it generously
Wont give up till i hit a 700+

Senior Manager
Joined: 13 May 2013
Posts: 472
Followers: 3

Kudos [?]: 160 [1] , given: 134

Re: At what speed was a train traveling on a trip when it had [#permalink]

### Show Tags

01 Aug 2013, 10:29
1
KUDOS
At what speed was a train traveling on a trip when it had completed half of the total distance of the trip?

(1) The trip was 460 miles long and took 4 hours to complete.
The train could have been moving at a slower speed for the first part of the trip then faster for the second part to complete the journey in 4 hours.
INSUFFICIENT

(2) The train traveled at an average rate of 115 miles per hour on the trip.
We know nothing about distance and it's possible that the train was traveling at a slower rate for the first part of the trip then faster for the second part of the trip to average out to 115 MPH.
INSUFFICIENT

1+2)
There still is not enough information to solve for this problem. We know that the train averaged 115MPH and that it took four hours to complete the trip (i.e. it took 4 hours) but the train could have moved slower for the first portion of the trip and faster for the second portion of the trip. there is no way of knowing for sure.
INSUFFICIENT

(E)
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 13468
Followers: 575

Kudos [?]: 163 [0], given: 0

Re: At what speed was a train traveling on a trip when it had [#permalink]

### Show Tags

15 Sep 2014, 06:42
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 13468
Followers: 575

Kudos [?]: 163 [0], given: 0

Re: At what speed was a train traveling on a trip when it had [#permalink]

### Show Tags

28 Apr 2016, 05:50
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Director
Joined: 24 Nov 2015
Posts: 564
Location: United States (LA)
Concentration: General Management, Marketing
GMAT 1: 700 Q49 V36
GRE 1: 328 Q167 V161
Followers: 11

Kudos [?]: 25 [0], given: 222

Re: At what speed was a train traveling on a trip when it had [#permalink]

### Show Tags

28 Apr 2016, 13:52
As we don't know whether the train is travelling at a constant speed,the answer is got to be E
Anyway for understanding here is a explaination
Statement 1 gives information about the total distance traveled in total time which will give us the average speed, but we can't deduce anything about the speed of the train when it had completed half of its distance, So insufficient

Statement 2 gives information about the average speed, but we can't deduce anything about the speed of the train when it had completed half of its distance, So insufficient
Combining both statements they are providing the same information
We only know that the average speed of the train was 115 miles per hour, which is not enough to determine the speed of the train when it had completed half of the total distance (230 miles) So insufficient
Senior Manager
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 464
Followers: 22

Kudos [?]: 193 [0], given: 2

Re: At what speed was a train traveling on a trip when it had [#permalink]

### Show Tags

14 May 2016, 06:52
At what speed was a train traveling on a trip when it had completed half of the total distance of the trip?

(1) The trip was 460 miles long and took 4 hours to complete.
(2) The train traveled at an average rate of 115 miles per hour on the trip.

Solution:

We need to determine at what speed a train was traveling when it completed ½ of its trip.

Statement One Alone:

The trip was 460 miles long and took 4 hours to complete.

With the information in statement one, we can determine the average speed of the train for the entire trip.

average speed = total distance/total time

average speed = 460/4

average speed = 115

Although we know that the train traveled at an average speed of 115 mph, we do not know whether the train traveled at a constant rate. Thus, we cannot determine the speed of the train when it completed half of the total distance. Statement one alone is not sufficient to answer the question. We can eliminate answer choices A and D.

Statement Two Alone:

The train traveled at an average rate of 115 miles per hour on the trip.

We see that statement two provides the same information as statement one and thus is also not sufficient to answer the question. We can eliminate answer choice B.

Statements One and Two Together:

Since statements one and two provide identical information and are each insufficient, we know that the statements together are also insufficient.

_________________

Jeffrey Miller
Jeffrey Miller

Manager
Joined: 09 Aug 2016
Posts: 55
Followers: 0

Kudos [?]: 2 [0], given: 2

At what speed was a train traveling on a trip when it had [#permalink]

### Show Tags

23 Sep 2016, 12:49
If you recall your physics class in high school you can solve this question in less than 30 seconds...

For starters: The question asks for the instantaneous speed of the train.

In this world there are ONLY two WAYs in order to be able to know the instantaneous speed of any object.

1) If someone tells you the speed @ that specific instance (lol)

2) If you have a speed equation with the unknown variable being the time, i.e. s(t) = function of speed ...
For example if we were in a position to derive from the given info an equation with 1 unknown like fore example..

Speed = 2t + 3
OR
Speed = a*t^2 + t + t/2 + c/g ETC ... OR any type of equation with a single variable t for time

then the only thing you need to do is replace the variable t with the time instance asked in the question and you are done. Although be very careful with the units of t.

This question doesn't do any of the two so you should be able to pick E very quickly.

Some might argue that the constant rate might cause a problem but hey this is nothing more than an equation with 0 unknown or in other words it will have the form y=b. Since we talk for speed and time for convenience Speed = α where α can be any value.

So if the question was saying that for a journey of Gazillion hours the speed of the train was constant at a m/s then you know that s = a which means that throughout the whole journey its speed was CONSTANT and never changed.
At what speed was a train traveling on a trip when it had   [#permalink] 23 Sep 2016, 12:49
Similar topics Replies Last post
Similar
Topics:
3 A train traveled from station X to station Y at a constant speed of 88 3 23 Jun 2016, 02:01
What was Bill's average speed on his trip of 250 miles from New York 2 28 Mar 2016, 01:23
28 A train traveled from Station A to Station B at an average speed of 80 8 04 Jun 2014, 23:00
80 During a 40-mile trip, Marla traveled at an average speed of 16 27 Apr 2010, 08:55
13 During a 40-mile trip, Marla traveled at an average speed of 5 19 May 2008, 17:25
Display posts from previous: Sort by