Last visit was: 19 May 2025, 13:49 It is currently 19 May 2025, 13:49
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.
Close
Request Expert Reply
Confirm Cancel
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 19 May 2025
Posts: 101,531
Own Kudos:
Given Kudos: 93,557
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 101,531
Kudos: 725,532
 [27]
Kudos
Add Kudos
27
Bookmarks
Bookmark this Post
Most Helpful Reply
User avatar
BhishmaNaidu99
Joined: 22 Sep 2018
Last visit: 29 Jun 2020
Posts: 72
Own Kudos:
85
 [6]
Given Kudos: 95
Posts: 72
Kudos: 85
 [6]
2
Kudos
Add Kudos
4
Bookmarks
Bookmark this Post
General Discussion
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 19 May 2025
Posts: 101,531
Own Kudos:
725,532
 [2]
Given Kudos: 93,557
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 101,531
Kudos: 725,532
 [2]
1
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
User avatar
eakabuah
User avatar
Retired Moderator
Joined: 18 May 2019
Last visit: 15 Jun 2022
Posts: 782
Own Kudos:
Given Kudos: 101
Posts: 782
Kudos: 1,105
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Let the time taken for the flight from A to B to Tab and the time from B to A be Tba. Let the speed of the plane be S, and the time difference be Td.
Then from the information provided above, the following equations can be formed.
Tab=7-td --------(1)
Tba=4+td--------(2)
Sab = S+50 -----(3)
Sba = S-50 ------(4)

Since the plane would cover the same distance in a trip from A to B and B to A, Average Speed, Sav, =[(S+50)+(S-50)]/2 = 2S/2 = S.
Average time, Tav, = [(4+td)+(7-td)] = 11/2 = 5.5hrs.

Sav = S = Average distance Between A and B / Average Time = 3000/5.5 = 545 approximately 550km/hr

The answer is, therefore B.
avatar
chanyb
Joined: 30 Nov 2019
Last visit: 11 May 2021
Posts: 48
Own Kudos:
18
 [3]
Given Kudos: 2
Location: Lebanon
GMAT 1: 670 Q46 V36
GMAT 2: 690 Q50 V34
GMAT 2: 690 Q50 V34
Posts: 48
Kudos: 18
 [3]
1
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
T1 + T2 = 4 + 7 = 11 hours
\(T1=\frac{D1}{V1}=\frac{3000}{(S+50)}\)
\(T2= \frac{D2}{V2}=\frac{3000}{(S-50)}\)
\(\frac{3000}{(S+50)}+\frac{3000}{(S-50)}=11\)

At this stage you can either solve the equation (not recommended) or plug in the numbers. 550 is a perfect fit:

\(\frac{3000}{(500+50)}+\frac{3000}{(550-50)}=5+6=11\)

Answer is B
avatar
Foreheadson
Joined: 22 Jun 2020
Last visit: 24 Sep 2022
Posts: 152
Own Kudos:
88
 [2]
Given Kudos: 120
Location: Georgia
Concentration: Finance, General Management
GMAT 1: 720 Q51 V38
GPA: 3.71
GMAT 1: 720 Q51 V38
Posts: 152
Kudos: 88
 [2]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Ok, So from A to B the plane would need 3000/(550+50)=5 hours right? but the problem says it needs 4 hours. how come?
User avatar
udaypratapsingh99
Joined: 12 Jan 2019
Last visit: 04 Mar 2025
Posts: 400
Own Kudos:
Given Kudos: 372
Location: India
Concentration: Strategy, Leadership
GMAT 1: 660 Q47 V34
Products:
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Foreheadson
Ok, So from A to B the plane would need 3000/(550+50)=5 hours right? but the problem says it needs 4 hours. how come?

Can you highlight, from which part of the question you inferred that it needs 4 hours?
I guess, the problem doesn't say that it needs 4 hours.
User avatar
martinfzb
Joined: 05 Sep 2022
Last visit: 19 Dec 2022
Posts: 24
Own Kudos:
16
 [1]
Given Kudos: 1
Posts: 24
Kudos: 16
 [1]
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
After got the 7 hours for BA and 4 hours for AB, we can see that the time zone difference must be 3/2=1.
Adjusting the travel time by 1 hour, we can get the actual flying time for BA and AB are 6 and 5.
Considering the impact of wind speed, we assume the constant flying speed is S, then we can get two equations
(S -50)*6 hours = 3000 for BA trip, the S, the constant speed, is 3300/6=550
(S+50)*5 hours = 3000 for AB trip, the constant is 2700/5= 550, same as above.
User avatar
samarpan.g28
Joined: 08 Dec 2023
Last visit: 19 May 2025
Posts: 319
Own Kudos:
95
 [1]
Given Kudos: 1,234
Location: India
Concentration: Strategy, Operations
GPA: 8.88
WE:Engineering (Technology)
Products:
Posts: 319
Kudos: 95
 [1]
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
Bunuel
Cities A and B are in different time zones. A is located 3000 km east of B. The table below describes the schedule of an airline operating non-stop flights between A and B. All the times indicated are local and on the same day.

Assume that planes cruise at the same speed in both directions. However, the effective speed is influenced by a steady wind blowing from east to west at 50 km per hour.

What is the plane’s cruising speed in km per hour?

(A) 500
(B) 550
(C) 600
(D) 700
(E) Cannot be determined


Are You Up For the Challenge: 700 Level Questions


Alright, total time 7+4=11 hrs.
The problem is similar to boat and stream-related ones.
Let the speed of the plane be x km/hr. Wind blowing from East to West at 50 km/hr.
So downstream speed i.e. East to West i.e. A to B is (x+50). Upstream speed i.e. West to East i.e. B to A is (x-50).
Speed=Distance/Time or, Time=Distance/Speed.
Total time 3000/(x+50) + 3000/(x-50) which is equal to 11 hrs.
Put the options given and check. x=550 matches so correct answer is (B).
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 36,893
Own Kudos:
Posts: 36,893
Kudos: 989
Kudos
Add Kudos
Bookmarks
Bookmark this Post
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.
Moderators:
Math Expert
101531 posts
PS Forum Moderator
585 posts