NEW HERE? LEARN MORE
closeclose
Last visit was: 28 Apr 2024, 13:51 It is currently 28 Apr 2024, 13:51
Decision Tracker
My Rewards
New posts
New comers' posts

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

Two trains are traveling in the same direction at 50 kmph and 30 kmph.

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92977
Own Kudos [?]: 619704 [8]
Given Kudos: 81613
Send PM
CAT Tests Forum Quiz Mode
Two trains are traveling in the same direction at 50 kmph and 30 kmph. [#permalink] New post   03 Jan 2020, 02:25
8
Bookmarks
Expert Reply
00:00
A
B
C
D
E

Difficulty:

35% (medium)

Question Stats:

72% (01:59) correct 28% (02:18) wrong based on 134 sessions
Hide Show timer Statistics
Two trains are traveling in the same direction at 50 kmph and 30 kmph. The faster train crosses a man sitting in the slower train in 18 seconds. Find the length of the faster train.

A. 80 mts
B. 100 mts
C. 120 mts
D. 125 mts
E. 150 mts
ShowHide Answer
Official Answer
B
avatar
B
Stonely
Intern
Intern
Joined: 25 Nov 2019
Posts: 34
Own Kudos [?]: 29 [2]
Given Kudos: 7
Send PM
Re: Two trains are traveling in the same direction at 50 kmph and 30 kmph. [#permalink] New post   03 Jan 2020, 13:40
2
Kudos
we are talking about relative speed 50-30=20kph
20000m/h*1h/60min*1min/60sec
200/36=5.555555m/s
5.55555 m/s*18 s=99.999999 meters

the guy timing must have had a shaky finger and miss timed just a little ;)
answer is B
User avatar
S
Jawad001
Manager
Manager
Joined: 14 Sep 2019
Posts: 223
Own Kudos [?]: 138 [3]
Given Kudos: 31
Send PM
Re: Two trains are traveling in the same direction at 50 kmph and 30 kmph. [#permalink] New post   04 Jan 2020, 11:00
2
Kudos
Relative speed =(50-30) = 20 kmph
= 20(5/18) msec

Distance = 20*(5/18) * 18 meter
= 20*5
= 100 meter(B)
avatar
B
hellothere88
Manager
Manager
Joined: 18 Dec 2017
Posts: 159
Own Kudos [?]: 18 [2]
Given Kudos: 13
Send PM
Re: Two trains are traveling in the same direction at 50 kmph and 30 kmph. [#permalink] New post   06 Nov 2020, 04:51
2
Kudos
Jawad001 wrote:
Relative speed =(50-30) = 20 kmph
= 20(5/18) msec

Distance = 20*(5/18) * 18 meter
= 20*5
= 100 meter(B)


where do you get the 5 in 20(5/18) from?
avatar
S
Abhibarua
Intern
Intern
Joined: 31 Jan 2021
Posts: 45
Own Kudos [?]: 33 [1]
Given Kudos: 99
Location: Bangladesh
GMAT 1: 760 Q50 V44
Send PM
Re: Two trains are traveling in the same direction at 50 kmph and 30 kmph. [#permalink] New post   12 Apr 2021, 04:54
1
Kudos
The faster train goes 50 - 30 = 20 kmph faster than the slower train. In other words, if the slower train stands still (i.e. speed =0), the faster train travels at 20 kmph.

In 3600 seconds the faster train travels 20,000 meters

In 18 seconds the faster train travels (20,000 X 18)/ 3600 = 100 meters.

Option: B.
User avatar
B
summerbummer
Manager
Manager
Joined: 16 Jul 2020
Posts: 56
Own Kudos [?]: 10 [0]
Given Kudos: 138
Location: India
GMAT 1: 520 Q39 V23
GMAT 2: 600 Q42 V30
Send PM
Re: Two trains are traveling in the same direction at 50 kmph and 30 kmph. [#permalink] New post   14 Apr 2021, 11:29
Stonely wrote:
we are talking about relative speed 50-30=20kph
20000m/h*1h/60min*1min/60sec
200/36=5.555555m/s
5.55555 m/s*18 s=99.999999 meters

the guy timing must have had a shaky finger and miss timed just a little ;)
answer is B

-------------------------------------------

But why are we calculating the relative speed when we just want to find out the length of the faster train wrt the man?

It can simply be: (50*1000*18)/(3600)?
User avatar
bumpbot
Non-Human User
Joined: 09 Sep 2013
Posts: 32726
Own Kudos [?]: 822 [0]
Given Kudos: 0
Send PM
Re: Two trains are traveling in the same direction at 50 kmph and 30 kmph. [#permalink] New post   24 Mar 2024, 17:35
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.
GMAT Club Bot
gmatclubot
Re: Two trains are traveling in the same direction at 50 kmph and 30 kmph. [#permalink]
24 Mar 2024, 17:35
Moderators:
Bunuel
Math Expert
92977 posts
yashikaaggarwal
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions