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:

Re: 'Distance/Speed/Time' Word Problems Made Easy [#permalink]

Show Tags

26 May 2014, 01:27

Great stuff sir . But how to use this method for problems related to train length , platform,bridges etc . Please show some some examples for those problems too.

Great stuff sir . But how to use this method for problems related to train length , platform,bridges etc . Please show some some examples for those problems too.

Re: 'Distance/Speed/Time' Word Problems Made Easy [#permalink]

Show Tags

01 Jun 2015, 05:19

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: 'Distance/Speed/Time' Word Problems Made Easy [#permalink]

Show Tags

05 May 2016, 13:13

An executive drove from home at an average speed of 30 mph to an airport where a helicopter was waiting. The executive boarded the helicopter and flew to the corporate offices at an average speed of 60 mph. The entire distance was 150 miles; the entire trip took three hours. Find the distance from the airport to the corporate offices.

in the above example why cant distance row of flying cannot be taken as "150-x" and that of driving as "x" (in that table method scheme).because when i take as above mentioned then x equals to 30 which is wrong so plz can u help me that

An executive drove from home at an average speed of 30 mph to an airport where a helicopter was waiting. The executive boarded the helicopter and flew to the corporate offices at an average speed of 60 mph. The entire distance was 150 miles; the entire trip took three hours. Find the distance from the airport to the corporate offices.

in the above example why cant distance row of flying cannot be taken as "150-x" and that of driving as "x" (in that table method scheme).because when i take as above mentioned then x equals to 30 which is wrong so plz can u help me that

distance-speed-time-word-problems-made-easy-87481

You can. x is the driving distance which you get as 30. So the flying distance was 150 - x = 120 (this is what is asked).

On the other hand, consider using ratios and weighted averages here. Speeds are 30 and 60 and average speed is 150/3= 50 mph. So ratio of time taken in each case = td/tf = (60 - 50)/(50 - 30) = 1:2 For 1 hour, he was driving and for 2 hours he was flying. Distance for which he flew = 60*2 = 120 miles

P.S. - Ask your doubt in the same thread as the original question. If you want some specific people to reply to your doubt, tag them in your post.
_________________

Re: 'Distance/Speed/Time' Word Problems Made Easy [#permalink]

Show Tags

06 May 2016, 11:21

VeritasPrepKarishma mam i read your weighted average topic in the blog which was ossom..but can u help me with a little confusion which is how do i choose or known in a question that which one is the correct weight that i have to take because if i take wrong weight then i will land up to a wrong answer in topics like time speed distance etc..

'Distance/Speed/Time' Word Problems Made Easy [#permalink]

Show Tags

07 May 2016, 10:33

Thanks for this amazing post!

Now, I am confident with my Speed, Distance Time concepts.

What I want to ask is: Do the practice questions in this post cover the "only types" of questions that could appear in the GMAT? Or has any type of question been left out?

VeritasPrepKarishma mam i read your weighted average topic in the blog which was ossom..but can u help me with a little confusion which is how do i choose or known in a question that which one is the correct weight that i have to take because if i take wrong weight then i will land up to a wrong answer in topics like time speed distance etc..

Now, I am confident with my Speed, Distance Time concepts.

What I want to ask is: Do the practice questions in this post cover the "only types" of questions that could appear in the GMAT? Or has any type of question been left out?

There is no exhaustive list of "types of questions" that could appear on GMAT. GMAC keeps coming up with innovative ways of testing the same concepts especially at the higher range of difficulty. But if you understand your concepts well, there is no reason for you to be unable to tackle those questions.
_________________

Re: 'Distance/Speed/Time' Word Problems Made Easy [#permalink]

Show Tags

26 Oct 2016, 05:39

Check the distance between any cities in England on a map of the world.

This calculator will calculate the distance between the cities on a map of the world will always help anyone who wants to know the exact distance between the cities and countries of the world.

'Distance/Speed/Time' Word Problems Made Easy [#permalink]

Show Tags

29 Dec 2016, 05:40

sriharimurthy wrote:

Motion in Same Direction (Overtaking): The first thing that should strike you here is that at the time of overtaking, the distances traveled by both will be the same.

Very good work and thanks for your post.

I have a small comment for this statement as is not true for all "Same Direction + Overtaking" cases and I will explain this by using two examples.

Example 1) Assume that we have the classic overtaking question where 2 objects A, B move on the same path with SA > SB and start from the same point. Also assume that B started first and then after x hours A begins to move. At this case the they will meet at some point where their distances (with reference to the starting point) will be equal. Hence we can calculate the duration of the journey for A and B etc...

Example2) Assume exactly the same scenario BUT THE TWIST is that object B has different starting point than A and for the sake of the example lets say that this distance difference is Y (in km). If both objects start moving at the same time they will meet after T time units (i.e. T hrs). The case though is that object A and B they will not have covered the same distance, with reference the starting moving instance, because object B will had covered D km and object A (D+Y) km.

As you can see both question are in the same category but this small twist in example 2 is a game-changer. These small twists are quite confusing and misleading, so perhaps your definitions require some clarification.

Re: 'Distance/Speed/Time' Word Problems Made Easy [#permalink]

Show Tags

31 Jul 2017, 22:50

VeritasPrepKarishma wrote:

dkj1984 wrote:

Example 2. An executive drove from home at an average speed of 30 mph to an airport where a helicopter was waiting. The executive boarded the helicopter and flew to the corporate offices at an average speed of 60 mph. The entire distance was 150 miles; the entire trip took three hours. Find the distance from the airport to the corporate offices.

Hi ,

Can someone please let me know what would be the average sped in this case .

Will it be total distance / total time = 150 / 3 or will it be 2ab/a+b = 2(30*60) / 90

Please advise.

Thanks!

Regards, Divya

I will clear your doubt but first let me give you some unsolicited 'gyan'. When dealing with formulas, remember two things: 1. Do not learn up formulas without knowing the assumptions made to derive them. 2. Make sure you understand how they are derived and the starting point.

Average speed is always Total Distance/Total Time.

1. The formula 2ab/(a+b) assumes that the distance traveled at speed a is the same as the distance traveled at speed b. Say distance traveled in each case is 1 km. 2. Derivation: Average Speed = Total Distance/Total Time = (1+1)/(1/a + 1/b) = 2ab/(a+b) So in case you have three speeds a, b and c, you know how to get the average speed in that case too.

Coming to this question, the formula is not used here because it doesn't say that the distance traveled at the two speeds is the same. Average Speed = Total distance/Total Time = 150/3 = 50 km/hr

Now there are two ways to handle it: 1. Weighted averages 2. Using algebra

Weighted Averages Method: This now becomes a weighted average problem since you have two speeds and their average is known. The weights will be the time for which the speeds were maintained. w1/w2 = (60 - 50)/(50 - 30) = 1:2 So plane travel lasted 2 hrs and car travel lasted 1 hr. Distance traveled by plane = 2*60 = 120 km

Algebra Method: Let time for which he traveled by plane is t hrs. 50 = (t*60 + (3-t)*30)/3 150 = 60t - 30t + 90 t = 2 hrs So plane travel lasted 2 hrs. Distance traveled by plane = 2*60 = 120 km

Thanks for the solution. However, please explain why the "The weights will be the time for which the speeds were maintained" in the weighted average method. How is the ratio of average speed giving us the ration of time ?

Example 2. An executive drove from home at an average speed of 30 mph to an airport where a helicopter was waiting. The executive boarded the helicopter and flew to the corporate offices at an average speed of 60 mph. The entire distance was 150 miles; the entire trip took three hours. Find the distance from the airport to the corporate offices.

Hi ,

Can someone please let me know what would be the average sped in this case .

Will it be total distance / total time = 150 / 3 or will it be 2ab/a+b = 2(30*60) / 90

Please advise.

Thanks!

Regards, Divya

I will clear your doubt but first let me give you some unsolicited 'gyan'. When dealing with formulas, remember two things: 1. Do not learn up formulas without knowing the assumptions made to derive them. 2. Make sure you understand how they are derived and the starting point.

Average speed is always Total Distance/Total Time.

1. The formula 2ab/(a+b) assumes that the distance traveled at speed a is the same as the distance traveled at speed b. Say distance traveled in each case is 1 km. 2. Derivation: Average Speed = Total Distance/Total Time = (1+1)/(1/a + 1/b) = 2ab/(a+b) So in case you have three speeds a, b and c, you know how to get the average speed in that case too.

Coming to this question, the formula is not used here because it doesn't say that the distance traveled at the two speeds is the same. Average Speed = Total distance/Total Time = 150/3 = 50 km/hr

Now there are two ways to handle it: 1. Weighted averages 2. Using algebra

Weighted Averages Method: This now becomes a weighted average problem since you have two speeds and their average is known. The weights will be the time for which the speeds were maintained. w1/w2 = (60 - 50)/(50 - 30) = 1:2 So plane travel lasted 2 hrs and car travel lasted 1 hr. Distance traveled by plane = 2*60 = 120 km

Algebra Method: Let time for which he traveled by plane is t hrs. 50 = (t*60 + (3-t)*30)/3 150 = 60t - 30t + 90 t = 2 hrs So plane travel lasted 2 hrs. Distance traveled by plane = 2*60 = 120 km

Thanks for the solution. However, please explain why the "The weights will be the time for which the speeds were maintained" in the weighted average method. How is the ratio of average speed giving us the ration of time ?

Re: 'Distance/Speed/Time' Word Problems Made Easy [#permalink]

Show Tags

23 Aug 2017, 02:50

gmatdelhi wrote:

Thanks a lot for this really helpful post! I used to go for CAT coaching with TIME institute about 2 years back...and I thought the method they taught to solve DST questions was unbeatable...but urs makes it even simpler, and so quick! If I save any time on GMAT while solving DST questions, the credit will def go to you!

Example 5. The presented solution is 21mph. Should this not also be the total average speed?

However the weighted average speed is calculated as 20.57 =((24*3)+(18*4))/(3+4).

You also get 20.57 if you calculate the total average speed with the total distance and the total time =144/7?

Could someone please explain why the table is not consistent in this example?

No. The answer 21 is the speed of the boat in calm water. It is not the average speed of the boat for the entire trip. The speed of the boat upstream was 18 and downstream was 24. For these speeds, 21 would be the weighted average in case the boat had travelled at the two speeds for the same time. But actually, the boat travelled at the two speeds for the same distance. In that case, the average speed is 2ab/(a+b), not (a+b)/2.
_________________

Re: 'Distance/Speed/Time' Word Problems Made Easy [#permalink]

Show Tags

13 Sep 2017, 05:07

Thank you very much @VeritasPrepKarishm However for me it is still not clear why the total average speed does not equal the boat speed in still water. The current helps you downstream as much as it works against you when you go upstream. This means that when the boat travels the same route without any current it takes the same amount of time 7 hours for 144miles. So in calm water the total average speed is still 20.57mph and not 21mph?

Thank you very much @VeritasPrepKarishm However for me it is still not clear why the total average speed does not equal the boat speed in still water. The current helps you downstream as much as it works against you when you go upstream. This means that when the boat travels the same route without any current it takes the same amount of time 7 hours for 144miles. So in calm water the total average speed is still 20.57mph and not 21mph?

Ok, think of it in another way:

Speed of boat while going downstream is 24 mph and while going upstream is 18 mph. If the boat travels at each speed for 1 hour, the average speed of the boat is 21 mph, that's correct. Now think, what if the boat travels for longer time at 18 mph and for shorter time at 24 mph? Will the average speed still be 21 mph for the entire trip? No, right? When the boat travels equal distances at the two speeds, this is exactly what happens. It takes longer at slower speed so it travels at the slower speed for longer and at the higher speed for shorter period of time. Hence, as we see, in this case the average speed decreases to 20.57 mph from 21 mph.

MBA Acceptance Rate by Undergraduate Major Many applicants may wonder if their undergraduate major impacts their chance of getting into business school. Admissions data suggests that your college major...

MBA Waitlist Acceptance Rate Analysis (with Class of 2019 data) One of the most frustrating parts of the MBA application process is waiting to hear back from the...

As you can see in this score card, Section 5 was not "best" section according to this criteria. However, I want to especially dedicate this article to the best...