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 350,000 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:

A car traveled 75% of the way from town A to town B at an [#permalink]
27 Mar 2013, 06:21

1

This post received KUDOS

2

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

55% (hard)

Question Stats:

68% (02:45) correct
32% (02:14) wrong based on 197 sessions

A car traveled 75% of the way from town A to town B at an average speed of 50 miles per hour. The car travels at an average speed of S miles per hour for the remaining part of the trip. The average speed for the entire trip was 40 miles per hour. What is S ?

Re: A car traveled 75% of the way from town A to town B at [#permalink]
27 Mar 2013, 06:51

2

This post received KUDOS

Expert's post

1

This post was BOOKMARKED

summer101 wrote:

A car traveled 75% of the way from town A to town B at an average speed of 50 miles per hour. The car travels at an average speed of S miles per hour for the remaining part of the trip. The average speed for the entire trip was 40 miles per hour. What is S ?

A. 10 B. 20 C. 25 D. 30 E. 37.5

Say the entire distance is 200 miles. 75% of the distance = 150 miles. 25% of the distance = 50 miles.

Total time = 200/40 = 5 hours; Time spent to cover 150 miles = 150/50 = 3 hours.

Thus 50 miles was covered in 5-3=2 hours --> S = (speed) = (distance)/(time) = 50/2 = 25 miles per hour.

Re: A car traveled 75% of the way from town A to town B at an [#permalink]
27 Mar 2013, 20:08

1

This post received KUDOS

Let the distance from A to B be 200 miles. 75% of 200 miles = 150 miles.So time taken to cover that = 150/50 hrs = 3 hrs. [time taken = distance covered / speed ] So time taken to cover remaining distance = 50/s hrs.

Total time taken for the trip = 200/40 = 5 hrs. so, 3 + 50/s = 5 =>50/s = 2 => s = 25

Hence,Option C will be the answer. ------------------------------------------------ Please press KUDOS if you like my post. _________________

Re: A car traveled 75% of the way from town A to town B at [#permalink]
26 May 2014, 12:05

Bunuel wrote:

summer101 wrote:

A car traveled 75% of the way from town A to town B at an average speed of 50 miles per hour. The car travels at an average speed of S miles per hour for the remaining part of the trip. The average speed for the entire trip was 40 miles per hour. What is S ?

A. 10 B. 20 C. 25 D. 30 E. 37.5

Say the entire distance is 200 miles. 75% of the distance = 150 miles. 25% of the distance = 50 miles.

Total time = 200/40 = 5 hours; Time spent to cover 150 miles = 150/50 = 3 hours.

Thus 50 miles was covered in 5-3=2 hours --> S = (speed) = (distance)/(time) = 50/2 = 25 miles per hour.

Answer: C.

I tried to solve it a different way... using weighted averages but hit a wall... Can you see where my logic fails?

Since the first part of the trip was 3/4 and the last was 1/4, this is what I got in my diagram:

S-----40-----50

----1-----3-----

When doing the cross multiplication, I get (50-40)/(40-S) = 3/1 -> I get S=110/3.

Re: A car traveled 75% of the way from town A to town B at [#permalink]
26 May 2014, 19:36

1

This post received KUDOS

Expert's post

ronr34 wrote:

Bunuel wrote:

summer101 wrote:

A car traveled 75% of the way from town A to town B at an average speed of 50 miles per hour. The car travels at an average speed of S miles per hour for the remaining part of the trip. The average speed for the entire trip was 40 miles per hour. What is S ?

A. 10 B. 20 C. 25 D. 30 E. 37.5

Say the entire distance is 200 miles. 75% of the distance = 150 miles. 25% of the distance = 50 miles.

Total time = 200/40 = 5 hours; Time spent to cover 150 miles = 150/50 = 3 hours.

Thus 50 miles was covered in 5-3=2 hours --> S = (speed) = (distance)/(time) = 50/2 = 25 miles per hour.

Answer: C.

I tried to solve it a different way... using weighted averages but hit a wall... Can you see where my logic fails?

Since the first part of the trip was 3/4 and the last was 1/4, this is what I got in my diagram:

S-----40-----50

----1-----3-----

When doing the cross multiplication, I get (50-40)/(40-S) = 3/1 -> I get S=110/3.

Why is this failing?

The weight when calculating average speed is time, not distance. This means that when you write (50-40)/(40-S) = 3/1, you are assuming that the car traveled 75% of the TIME at speed S and 25% of the time at speed 50 mph.

Re: A car traveled 75% of the way from town A to town B at an [#permalink]
23 Jun 2014, 20:23

Hey Bunuel,

How do we know when is it ok to plug in an assumed value? In this case, I was hesitant to plug in a value thinking that it may impact the calculation wrongly. Also, there simply isnt enough time to plug in 2 values and check if they each give the same answer!

Re: A car traveled 75% of the way from town A to town B at an [#permalink]
24 Jun 2014, 03:12

Expert's post

1

This post was BOOKMARKED

ravih wrote:

Hey Bunuel,

How do we know when is it ok to plug in an assumed value? In this case, I was hesitant to plug in a value thinking that it may impact the calculation wrongly. Also, there simply isnt enough time to plug in 2 values and check if they each give the same answer!

Well, the question talks only about the percentages of the total distance, so whatever the actual distance is the answer must remain the same. _________________

Re: A car traveled 75% of the way from town A to town B at an [#permalink]
24 Jun 2014, 21:58

Some where i read that average speed = 2s1*s2/(s1+s2). Clearly this is not applicable in current scenario. Can some one recollect when does this average speed formula holds good?

Re: A car traveled 75% of the way from town A to town B at an [#permalink]
24 Jun 2014, 22:44

Expert's post

GMatAspirerCA wrote:

Some where i read that average speed = 2s1*s2/(s1+s2). Clearly this is not applicable in current scenario. Can some one recollect when does this average speed formula holds good?

It applies when the distance traveled at the two speeds is the same.

MBA Acceptance Rate by Country Most top American business schools brag about how internationally diverse they are. Although American business schools try to make sure they have students from...

McCombs Acceptance Rate Analysis McCombs School of Business is a top MBA program and part of University of Texas Austin. The full-time program is small; the class of 2017...