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:

Carl drove from his home to the beach at an average speed of [#permalink]

Show Tags

16 Nov 2003, 18:20

1

This post received KUDOS

5

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

25% (medium)

Question Stats:

77% (02:43) correct
23% (02:07) wrong based on 344 sessions

HideShow timer Statistics

Carl drove from his home to the beach at an average speed of 80 kilometers per hour and returned home by the same route at an average speed of 70 kilometers per hour. If the trip home took 1/2 hour longer than the trip to the beach, how many kilometers did Carl drive each way?

I think you can solve such problems in lesser time, if you always follow one approach consistently. You can always solve any such problem by using the Distance formula. The moment you see distances/times or speeds put down the formula and try to fit in given information.

Distance= Speed * Time.

Distance - Is being asked so don't know - D
Speed - Given 80
Time - don't know so T.
D= 80*T

Wait.. speed is given twice. So put down the equation again.
Distance - D2
Speed - 70
Time - don't know so T2
D2 = 70 * T2

What all information do we have ?
1) The distance is the same. So D=D2
2) The time taken to return is 1/2 hr more than the time taken to go to the beach => T + 1/2 = T2

Therefore D=80*T = 70*(T+1/2) => T= 3.5 => D= 80*3.5= 280. D is the answer.

Usually we take more time to solve when we don't get an exact sense of the question or if we are torn between two ore more methods to solve. This usually happens if you can sense the possibility of easy solution but are not quite clear about what it is.

Probably the intuitive method would be -> In half an hour at 70 km/hr Carl would have travelled 35 k.m. At a difference in speed of 10 km/hr how much time would it take to fall behind by 35 km? 35/10 = 3.5 hrs. So the distance travelled in these 3.5 hrs = 3.5 * 80
(Think of somebody else starting from the other side at the same time (and the speed of 10km/hr) Carl starts his return. In the time Carl would take to go to the beach, our guy will meet Carl and would have travelled 35 km. Therefore, the time taken by him =35/10 which will also be equal to the time taken by Carl to go to the beach.)

But it's difficult to rely on being able to use such intuitive approaches during the test. Such approaches tend to be problem specific and if you are under pressure, you may find it difficult to think clearly enough to get such solutions. I think it would be better to go to the test with some straight forward methods for such straight questions and leave the intuitive thinking for the really tough questions where you may not have the easier alternative.

Or, you can solve few speed/distance problems before the test. This usually helps.

Re: Carl drove from his home to the beach at an average speed of [#permalink]

Show Tags

11 Apr 2014, 00:51

1

This post received KUDOS

guy123 wrote:

Carl drove from his home to the beach at an average speed of 80 kilometers per hour and returned home by the same route at an average speed of 70 kilometers per hour. If the trip home took hour longer than the trip to the beach, how many kilometers did Carl drive each way?

Re: Carl drove from his home to the beach at an average speed of [#permalink]

Show Tags

11 Apr 2014, 01:02

1

This post received KUDOS

ind23 wrote:

guy123 wrote:

Carl drove from his home to the beach at an average speed of 80 kilometers per hour and returned home by the same route at an average speed of 70 kilometers per hour. If the trip home took hour longer than the trip to the beach, how many kilometers did Carl drive each way?

(A) 350 (B) 345 (C) 320 (D) 280 (E) 240

Is it half hour longer or hour longer?

Can someone please edit the question? It should be 1/2 hr; 1 hr gives the answer = 560 _________________

Re: Carl drove from his home to the beach at an average speed of [#permalink]

Show Tags

11 Apr 2014, 04:00

1

This post received KUDOS

Expert's post

ind23 wrote:

guy123 wrote:

Carl drove from his home to the beach at an average speed of 80 kilometers per hour and returned home by the same route at an average speed of 70 kilometers per hour. If the trip home took hour longer than the trip to the beach, how many kilometers did Carl drive each way?

(A) 350 (B) 345 (C) 320 (D) 280 (E) 240

Is it half hour longer or hour longer?

It's 1/2 hour. Edited the original post. Thank you. _________________

Yep, agree on D. I'd also agree with dj's explanation. That is a very simple and short way of doing this. The key is recognizing how to set up the equation.

Re: Carl drove from his home to the beach at an average speed of [#permalink]

Show Tags

08 Apr 2014, 19:38

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: Carl drove from his home to the beach at an average speed of [#permalink]

Show Tags

08 Apr 2014, 21:47

[quote="guy123"]Carl drove from his home to the beach at an average speed of 80 km/hr and returned home by the same route at an average speed of 70km/hr. If the trip home took 1/2 hour longer than the trip to the beach, how many km did Carl drive each way?

A)350 B)345 C)320 D)280 E)240

Let us backsolve here.

The answer option has to be divisible by 7 to give us 1/2.

Let us try 280 km. Time taken will be 3.5 hours and 4 hours.

Re: Carl drove from his home to the beach at an average speed of [#permalink]

Show Tags

23 Oct 2014, 02:27

Distances are same. Let d be the time taken to beach . So distance to beach be 80t . Distance to home will be 70(t+0.5) . Equating both distances, 80t=70t+70(0.5) t=3.5

substituting the value in 80t, we get the distance as 280 _________________

Re: Carl drove from his home to the beach at an average speed of [#permalink]

Show Tags

24 Oct 2015, 15:07

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. _________________

Part 2 of the GMAT: How I tackled the GMAT and improved a disappointing score Apologies for the month gap. I went on vacation and had to finish up a...

Cal Newport is a computer science professor at GeorgeTown University, author, blogger and is obsessed with productivity. He writes on this topic in his popular Study Hacks blog. I was...

So the last couple of weeks have seen a flurry of discussion in our MBA class Whatsapp group around Brexit, the referendum and currency exchange. Most of us believed...