Last visit was: 24 Apr 2026, 01:38 It is currently 24 Apr 2026, 01:38
Home
Messages
Tests
Schools
Events
Close
GMAT Club Daily Prep
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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
User avatar
cleetus
User avatar
Joined: 25 Jan 2010
Last visit: 01 Oct 2015
Posts: 91
Own Kudos:
800
 [6]
Given Kudos: 40
Location: Calicut, India
Concentration: Finance
Posts: 91
Kudos: 800
 [6]
Towns X and Y are in countries P and Q respectively. X is 3600 km to 16 Aug 2011, 19:04
2
Kudos
Add Kudos
4
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

55% (hard)

Question Stats:

57% (01:19) correct 43% (03:50) wrong based on 7 sessions

History

Date
Time
Result
Not Attempted Yet
Towns X and Y are in countries P and Q respectively. X is 3600 km to the west of Y. An Airline operates non-stop flights between X and Y. Its schedule is tabulated as below. The given time is the local time on the same day.

Departure from Town Y at 4.00PM and Arrival at Town X at 7.30 PM
Departure from Town X at 3.00AM and Arrival at Town Y at 1.30 PM

The planes cruise at the same speed in both directions. However, a steady wind blows from Y to X at 75 KMPH. The effective speed of each plane is affected by this.

Find the time differance between X and Y and the spped at which each plane cruises in KMPH.

A) 2 hrs ; 425 KMPH
B) 2.5 hrs; 525 KMPH
C) 3 hrs; 475 KMPH
D) 4.5 hrs; 550 KMPH
E) 1.5 hrs; 450 KMPH
ShowHide Answer
Official Answer
B
User avatar
KarishmaB
User avatar
Joined: 16 Oct 2010
Last visit: 23 Apr 2026
Posts: 16,442
Own Kudos:
79,399
 [1]
Given Kudos: 485
Location: Pune, India
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 16,442
Kudos: 79,399
 [1]
Towns X and Y are in countries P and Q respectively. X is 3600 km to 16 Aug 2011, 21:30
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
cleetus
Any idea how to slove this without much caluclation steps... any easy shortcut methodes to get the answer in less than 2 mins ?


Towns X and Y are in countries P and Q respectively. X is 3600 km to the west of Y. An Airline operates non-stop flights between X and Y. Its schedule is tabulated as below. The given time is the local time on the same day.

Departure from Town Y at 4.00PM and Arrival at Town X at 7.30 PM
Departure from Town X at 3.00AM and Arrival at Town Y at 1.30 PM

The planes cruise at the same speed in both directions. However, a steady wind blows from Y to X at 75 KMPH. The effective speed of each plane is affected by this.

Find the time differance between X and Y and the spped at which each plane cruises in KMPH.

A) 2 hrs ; 425 KMPH
B) 2.5 hrs; 525 KMPH
C) 3 hrs; 475 KMPH
D) 4.5 hrs; 550 KMPH
E) 1.5 hrs; 450 KMPH
Show more

Consider this:
Departure from Town Y at 4.00PM and Arrival at Town X at 7.30 PM
Departure from Town X at 3.00AM and Arrival at Town Y at 1.30 PM

The plane leaves Y at 4:00 PM and is back next day at 1:30 PM i.e. it is out of Y for a total of 21.5 hrs.
The plane reaches X at 7:30 PM and leaves X at 3:00 AM i.e. it rests in X for a total of 7.5 hrs.
This means that it is traveling to and fro for a total of 14 hrs.

Now this question is just like boats and streams. First it travels with the wind so takes less time (downstream) and then it travels against the wind and takes more time (upstream)

Time taken from Y to X = 3600/(s+75)
Time taken from X to Y = 3600/(s - 75)

3600/(s+75) + 3600/(s - 75) = 14
Of course, I am not going to solve this equation. I will try some options. 525 looks good because it is bang in the middle. Also I like the 25 of 525 since it will lead to a better number when we subtract/add 75 to it.

3600/(600) + 3600/(450) = 14
6 + 8 = 14

525 satisfies the equation. Great! Answer is B.

If you want to further verify the time difference, think that from Y to X, the journey takes a total of 6 hrs (downstream). But you leave Y at 4:00 PM and reach X at 7:30 PM. You should reach at 10:00 PM Y time. Hence difference between X and Y time is 2.5 hrs.
User avatar
cleetus
User avatar
Joined: 25 Jan 2010
Last visit: 01 Oct 2015
Posts: 91
Own Kudos:
800
 [1]
Given Kudos: 40
Location: Calicut, India
Concentration: Finance
Posts: 91
Kudos: 800
 [1]
Towns X and Y are in countries P and Q respectively. X is 3600 km to 19 Aug 2011, 04:40
Kudos
Add Kudos
Bookmarks
Bookmark this Post
VeritasPrepKarishma
cleetus
Any idea how to slove this without much caluclation steps... any easy shortcut methodes to get the answer in less than 2 mins ?


Towns X and Y are in countries P and Q respectively. X is 3600 km to the west of Y. An Airline operates non-stop flights between X and Y. Its schedule is tabulated as below. The given time is the local time on the same day.

Departure from Town Y at 4.00PM and Arrival at Town X at 7.30 PM
Departure from Town X at 3.00AM and Arrival at Town Y at 1.30 PM

The planes cruise at the same speed in both directions. However, a steady wind blows from Y to X at 75 KMPH. The effective speed of each plane is affected by this.

Find the time differance between X and Y and the spped at which each plane cruises in KMPH.

A) 2 hrs ; 425 KMPH
B) 2.5 hrs; 525 KMPH
C) 3 hrs; 475 KMPH
D) 4.5 hrs; 550 KMPH
E) 1.5 hrs; 450 KMPH

Consider this:
Departure from Town Y at 4.00PM and Arrival at Town X at 7.30 PM
Departure from Town X at 3.00AM and Arrival at Town Y at 1.30 PM

The plane leaves Y at 4:00 PM and is back next day at 1:30 PM i.e. it is out of Y for a total of 21.5 hrs.
The plane reaches X at 7:30 PM and leaves X at 3:00 AM i.e. it rests in X for a total of 7.5 hrs.
This means that it is traveling to and fro for a total of 14 hrs.

Now this question is just like boats and streams. First it travels with the wind so takes less time (downstream) and then it travels against the wind and takes more time (upstream)

Time taken from Y to X = 3600/(s+75)
Time taken from X to Y = 3600/(s - 75)

3600/(s+75) + 3600/(s - 75) = 14
Of course, I am not going to solve this equation. I will try some options. 525 looks good because it is bang in the middle. Also I like the 25 of 525 since it will lead to a better number when we subtract/add 75 to it.

3600/(600) + 3600/(450) = 14
6 + 8 = 14

525 satisfies the equation. Great! Answer is B.

If you want to further verify the time difference, think that from Y to X, the journey takes a total of 6 hrs (downstream). But you leave Y at 4:00 PM and reach X at 7:30 PM. You should reach at 10:00 PM Y time. Hence difference between X and Y time is 2.5 hrs.
Show more

Thanks for that detailed explanation Karishma..... Great help. +1 to u. Ur exp always helps me in catching the concept.
User avatar
cleetus
User avatar
Joined: 25 Jan 2010
Last visit: 01 Oct 2015
Posts: 91
Own Kudos:
800
Given Kudos: 40
Location: Calicut, India
Concentration: Finance
Posts: 91
Kudos: 800
Towns X and Y are in countries P and Q respectively. X is 3600 km to 19 Aug 2011, 06:36
Kudos
Add Kudos
Bookmarks
Bookmark this Post
VeritasPrepKarishma
cleetus
Any idea how to slove this without much caluclation steps... any easy shortcut methodes to get the answer in less than 2 mins ?


3600/(s+75) + 3600/(s - 75) = 14
Of course, I am not going to solve this equation. I will try some options. 525 looks good because it is bang in the middle. Also I like the 25 of 525 since it will lead to a better number when we subtract/add 75 to it.

3600/(600) + 3600/(450) = 14
6 + 8 = 14

525 satisfies the equation. Great! Answer is B.

If you want to further verify the time difference, think that from Y to X, the journey takes a total of 6 hrs (downstream). But you leave Y at 4:00 PM and reach X at 7:30 PM. You should reach at 10:00 PM Y time. Hence difference between X and Y time is 2.5 hrs.
Show more

What if the question asks u to find only the time difference between two countries and no information about the speed, i.e, 525 km per hour is not mentioned in the question. Do u need to do the lengthy algebraic calculation for 3600/(s+75) + 3600/(s - 75) = 14 . Or is there any easy Go.
User avatar
KarishmaB
User avatar
Joined: 16 Oct 2010
Last visit: 23 Apr 2026
Posts: 16,442
Own Kudos:
79,399
Given Kudos: 485
Location: Pune, India
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 16,442
Kudos: 79,399
Towns X and Y are in countries P and Q respectively. X is 3600 km to 23 Aug 2011, 21:09
Kudos
Add Kudos
Bookmarks
Bookmark this Post
cleetus


What if the question asks u to find only the time difference between two countries and no information about the speed, i.e, 525 km per hour is not mentioned in the question. Do u need to do the lengthy algebraic calculation for 3600/(s+75) + 3600/(s - 75) = 14 . Or is there any easy Go.
Show more

You will almost never need to solve this equation and in GMAT, I can say will reasonable certainty that you will 'never ever' need to solve it the long way. In such questions time taken is generally an integral value.

Even if 525 is not there in the options, look at the big picture

3600/(s+75) + 3600/(s - 75) = 14

The two terms on the left hand side add up to give 14 hrs. Obviously the first term is smaller and the second term is greater. I can split 14 into 6 hrs and 8 hrs OR 5 and 9 OR 4 and 10 etc

Now, wind will have some effect on the time taken but it may not be very dramatic. So, I will first try 6 and 8.

I say, what if 3600/(s + 75) is 6 hrs? i.e. what if s+75 is 600? i.e. what if s is 525? I plug s = 525 in 3600/(s - 75) and see that I do get 8. Then s must be 525!
Had 6 and 8 not worked, I would have tried 5 and 9.

Another thing:
Say the equation is: 770/(s + 20) + 770/(s - 20) = 18
I can split 18 into 8 and 10 OR 7 and 11 etc.
I will not try 8 and 10 here because 770 is not divisible by 8 so no way can I get an integer value for the time i.e. I cannot get 8 hrs.
I will jump to 7 and 11 first.
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,965
Own Kudos:
1,117
Posts: 38,965
Kudos: 1,117
Towns X and Y are in countries P and Q respectively. X is 3600 km to 31 Jan 2019, 07:27
Kudos
Add Kudos
Bookmarks
Bookmark this Post
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.
Moderators:
Bunuel
Math Expert
109802 posts
Krunaal
Tuck School Moderator
853 posts