On a long stretch of east-west road, A and B are two points such that

Question

On a long stretch of east-west road, A and B are two points such that B is 350 km west of A. One car starts from A and another from B at the same time. If they move towards each other, then they meet after 1 hour. If they both move towards east, then they meet in 7 hrs. What is the difference between their speeds, in km per hour?

A. 20
B. 30
C. 40
D. 50
E. 60

Are You Up For the Challenge: 700 Level Questions

A. 20
B. 30
C. 40
D. 50
E. 60

Are You Up For the Challenge: 700 Level Questions

preetamsaha · Answer

Let the speeds of Cars are v and u. then, v+u=350———–1)
and v-u=350/7=50———-2)
So required difference in speeds=50 km/hr
 Correct answer D

globaldesi · Answer

let the seed of each car be 
A and B
given 
 \frac{350}{a+b }= 1 ---- (1)

Also 
 \frac{350}{ a-b} = 7 
or a-b = 50
thus D
 Bunuel  is D actually an answer
I am confused . this seems little straight forward or Did I miss something

fireagablast · Answer

350/(x+y) = 1
350/(x-y)=7

350 = x+y
50 = x-y

x=200
y=150
200-150=50

effatara · Answer

It appears that the information in the question stem that the cars meet after one hour when they are moving towards each other is not really needed to solve the problem.
Let the car starting from A be CA and the car from B be CB and their speeds 'sa' kmph and 'sb' kmph respectively. It is obvious that CB is the faster car since it manages to overtake CA at some point when they both travel eastward. 
Let us ignore the first part and focus on the fact that it takes CB seven hours to catch up with CA after they both start simultaneously (CA from point A and CB from point B) moving eastward.
The distance covered by CB in 7 hours is 7*sb kms which is equal to the 350 km plus the the distance covered by CA in 7 hours which is 7*sa kms.
7*sb = 350+7*sa....> (sb-sa) = 50 kmph. ANS: D

ScottTargetTestPrep · Answer

Let r = the speed of car 1 and s = the speed of car 2. We can create the following two equations:

r + s = 350

and

7r - 7s = 350

Dividing the second equation by 7, we have r - s = 50. So the difference between their speeds, (r - s), is 50 kmph.

Answer: D

Aviralft9 · Answer

B----------(350km)------------A

Va + Vb = 350 kmph
Let X be the distance A travels in 7 hrs.
Da = X = Va * 7;
Db = 350 + X = Vb * 7;

350 + Va*7 = Vb*7;
350 = (Vb - Va)*7;
Vb - Va = 350/7 = 50;

Correct Ans  = D;

Kinshook · Answer

Given: 
1. On a long stretch of east-west road, A and B are two points such that B is 350 km west of A. 
2. One car starts from A and another from B at the same time. If they move towards each other, then they meet after 1 hour.

Asked: If they both move towards east, then they meet in 7 hrs. What is the difference between their speeds, in km per hour?

B--------------------350 km ---------------------A

Let the speeds of A & B be x & y km/hr respectively

2. One car starts from A and another from B at the same time. If they move towards each other, then they meet after 1 hour. 
x + y = 350 km/hr (1)

If they both move towards east, then they meet in 7 hrs.
x - y = 350/7 = 50 km/hr (2)

IMO D

h31337u · Answer

On a long stretch of east-west road, A and B are two points such that B is 350 km west of A. One car starts from A and another from B at the same time. If they move towards each other, then they meet after 1 hour. If they both move towards east, then they meet in 7 hrs. What is the difference between their speeds, in km per hour?

A. 20
B. 30
C. 40
D. 50
E. 60

Are You Up For the Challenge: 700 Level Questions

A. 20
B. 30
C. 40
D. 50
E. 60

Let A be the speed of A in km
Let B be the speed of B in km

First, look at the question. 
We want to know A - B = ??

Second, translate sentences into an equation. 
 On a long stretch of east-west road, A and B are two points such that B is 350 km west of A. One car starts from A and another from B at the same time. If they move towards each other, then they meet after 1 hour. 
This sentence translates into an equation : A + B = 350 -- (1)

If they both move towards east, then they meet in 7 hrs.
 
This sentence translates into an equation : 7 x A = 350 + 7 x B. 
Divide this by 7, we get A = 50 + B -- (2)

Now, since we want to know A - B = ?, (2) alone can answer that. 
From (2), we get A - B = 50. 
 Therefore, the answer is 50.

bumpbot · Answer

Automated notice from GMAT Club BumpBot: 

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

 This post was generated automatically.

On a long stretch of east-west road, A and B are two points such that

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Problem Solving (PS) Questions

On a long stretch of east-west road, A and B are two points such that

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards