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 Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

72% (00:59) correct
28% (01:19) wrong based on 200 sessions

HideShow timer Statistics

Tough and Tricky questions: Distance/Rate Problems.

While on straight, parallel tracks, train A and train B are traveling at different constant rates. If train A is currently 2 miles behind train B, how many minutes from now will train A be 4 miles behind train B?

(1) Three minutes ago, train A was 1 mile behind train B.

(2) Train A is traveling at 80 miles per hour, and train B is traveling at 100 miles per hour.

Re: While on straight, parallel tracks, train A and train B are traveling [#permalink]

Show Tags

14 Nov 2014, 12:14

1

This post received KUDOS

statement 1: sufficient If 3 minutes ago train A was 1 mile behind and now train A is 2 miles behind, then 3 minutes from now train A will be 3 miles behind and 6 minutes from now train A will be 4 miles behind.

statement 2: sufficient Train A is 20mph slower than train B. Each hour train A will get 20 miles furthur behind, or 1 mile every 3 minutes.

Re: While on straight, parallel tracks, train A and train B are traveling [#permalink]

Show Tags

14 Nov 2014, 19:59

1

This post received KUDOS

1

This post was BOOKMARKED

Statement 1: Three minutes ago, train A was 1 mile behind train B.

To cover 1 extra mile between B and A, it takes 3 mins

Therefore, to cover 2 miles, it would take = 3*2 = 6 mins. Sufficient

Statement 2: Train A is traveling at 80 miles per hour, and train B is traveling at 100 miles per hour.

Relative speed = 20 miles/hr. Let t be the time when the distance between A and B becomes 2 miles. 20 * t = 2 or, t = 2/ 20 hours = 2/20*60 mins = 6 mins. Sufficient

Re: While on straight, parallel tracks, train A and train B are traveling [#permalink]

Show Tags

15 Nov 2014, 02:09

1

This post received KUDOS

Statement 1: From question - Train A is currently 2 miles behind train B From Statement - Three minutes ago, train A was 1 mile behind train B.

So, to cover 1 mile train takes 3 mins

Therefore, to cover another 2 miles, train will take = 3*2 = 6 mins. Sufficient. Options B,C,E are out

Statement 2: Speeds of both the trains are given, so we can calculate relative speed. Relative speed = 100 - 80 = 20 miles/hr. Now we know both speed and distance so it will be easy to calculate time. Sufficient Answer, D _________________

_________________

KUDOS is always a good way to thank anyone. It encourages someone to post more questions and also answers.

KUDOS Please if My post helps you in anyway. Your Kudos keep me alive [/color]

Tough and Tricky questions: Distance/Rate Problems.

While on straight, parallel tracks, train A and train B are traveling at different constant rates. If train A is currently 2 miles behind train B, how many minutes from now will train A be 4 miles behind train B?

(1) Three minutes ago, train A was 1 mile behind train B.

(2) Train A is traveling at 80 miles per hour, and train B is traveling at 100 miles per hour.

Kudos for a correct solution.

Official Solution:

While on straight, parallel tracks, train A and train B are traveling at different constant rates. If train A is currently 2 miles behind train B, how many minutes from now will train A be 4 miles behind train B?

We need to know how many minutes, \(t\), it will take for the distance between train A and train B to increase by 2 miles. The trains are moving at different yet constant speeds, and so the difference between their speeds is also constant. This difference is equivalent to the rate at which train B moves ahead of train A, and since \(\text{distance} = \text{rate} \times \text{time}\), or \(d=r \times t\), the distance between the two trains must also change at a constant rate.

Statement 1 says that 3 minutes ago, train A was 1 mile behind train B. Since train A is now 2 miles behind train B, train A must fall behind train B at a rate of 1 mile every 3 minutes. Train A needs to fall behind 2 more miles; that will take \(2 \times 3 = 6\) minutes. Statement 1 is sufficient to answer the question. Eliminate answer choices B, C, and E. The correct answer choice is either A or D.

Statement 2 gives the rates of both trains. Since the trains' speeds are given in miles per hour, we convert them to miles per minute by dividing them by 60, as there are 60 minutes in an hour. Thus, since train A is going 80 miles per hour, it is going \(\frac{80}{60} = \frac{8}{6} = \frac{4}{3}\) miles per minute; similarly, train B is going \(\frac{100}{60} = \frac{10}{6} = \frac{5}{3}\) miles per minute. So, in 3 minutes, train A goes 4 miles and train B goes 5 miles. Thus, train A falls 1 mile farther behind train B every 3 minutes. As we saw in looking at statement 1, this information is enough to answer the question. Statement 2 is also sufficient.

Re: While on straight, parallel tracks, train A and train B are traveling [#permalink]

Show Tags

05 Dec 2015, 12:48

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.
_________________

Re: While on straight, parallel tracks, train A and train B are traveling [#permalink]

Show Tags

19 Aug 2017, 20:33

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.
_________________

Version 8.1 of the WordPress for Android app is now available, with some great enhancements to publishing: background media uploading. Adding images to a post or page? Now...

“Keep your head down, and work hard. Don’t attract any attention. You should be grateful to be here.” Why do we keep quiet? Being an immigrant is a constant...

“Keep your head down, and work hard. Don’t attract any attention. You should be grateful to be here.” Why do we keep quiet? Being an immigrant is a constant...