Last visit was: 23 Jul 2024, 04:23 It is currently 23 Jul 2024, 04:23
Toolkit
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

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.

A train travels at an average speed of 90 km/hr without any stoppages.

SORT BY:
Tags:
Show Tags
Hide Tags
Math Expert
Joined: 02 Sep 2009
Posts: 94578
Own Kudos [?]: 643198 [23]
Given Kudos: 86728
GMAT Club Legend
Joined: 08 Jul 2010
Status:GMAT/GRE Tutor l Admission Consultant l On-Demand Course creator
Posts: 6027
Own Kudos [?]: 13819 [3]
Given Kudos: 125
Location: India
GMAT: QUANT+DI EXPERT
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
WE:Education (Education)
GMAT Club Legend
Joined: 18 Aug 2017
Posts: 8010
Own Kudos [?]: 4251 [1]
Given Kudos: 243
Location: India
Concentration: Sustainability, Marketing
GMAT Focus 1:
545 Q79 V79 DI73
GPA: 4
WE:Marketing (Energy and Utilities)
Retired Moderator
Joined: 10 Nov 2018
Posts: 536
Own Kudos [?]: 471 [3]
Given Kudos: 229
Location: India
Concentration: General Management, Strategy
GMAT 1: 590 Q49 V22
WE:Other (Retail)
Re: A train travels at an average speed of 90 km/hr without any stoppages. [#permalink]
1
Kudos
2
Bookmarks
Actual Speed of the train = 90 KM/Hr = 1.5 KM / Min
Distance Travelled = 60 KM, Speed = 1.5 Km / Min, hence time = 60/1.5=>40 Mins

Halt Minutes = 60 - 40 =>20 Mins
Intern
Joined: 04 Apr 2019
Posts: 4
Own Kudos [?]: 2 [0]
Given Kudos: 16
Re: A train travels at an average speed of 90 km/hr without any stoppages. [#permalink]
Don't we need to assume for that answer that we can ignore the deceleration of the train when arriving at a stop?
Manager
Joined: 09 Nov 2015
Posts: 201
Own Kudos [?]: 336 [1]
Given Kudos: 96
A train travels at an average speed of 90 km/hr without any stoppages. [#permalink]
1
Bookmarks
Let's say the distance the train travels is D kilometers. Thus, with stoppages it takes D/60 hrs and without stoppages it would have taken D/90 hrs. So for a D/60 hour trip, the train loses D/180 hrs (D/60 - D/90). Therefore, the time lost PER HOUR due to stoppages is:
(D/180)/(D/60)=1/3 hrs=20 minutes. Ans: C
Intern
Joined: 27 Dec 2019
Posts: 1
Own Kudos [?]: 1 [0]
Given Kudos: 45
Re: A train travels at an average speed of 90 km/hr without any stoppages. [#permalink]
Bunuel, can you please confirm the below thought process?

Avg Speed (w/ stops) = Distance / Total Time = 60 km/hr

Distance = (90 km/hr)(t1 hr) + (0 km/hr)(t2 hr) (km)
Total Time = t1 + t2 (hr)

Solve to get
t1/t2 = 2hr/1hr

In order to Avg 60 km/hr you need 2 hrs of 90 km/hr for every 1 hour the train is stopped (0 km/hr)
OR
1/3 of every hour = 20 minutes stopped C, 40 minutes running at 90 km/hr
Intern
Joined: 26 Jul 2019
Posts: 1
Own Kudos [?]: 0 [0]
Given Kudos: 41
Re: A train travels at an average speed of 90 km/hr without any stoppages. [#permalink]
effatara wrote:
Let's say the distance the train travels is D kilometers. Thus, with stoppages it takes D/60 hrs and without stoppages it would have taken D/90 hrs. So for a D/60 hour trip, the train loses D/180 hrs (D/60 - D/90). Therefore, the time lost PER HOUR due to stoppages is:
(D/180)/(D/60)=1/3 hrs=20 minutes. Ans: C

can you explain the reasoning behind (D/180)/(D/60) ??

Bunuel
Tutor
Joined: 16 Oct 2010
Posts: 15140
Own Kudos [?]: 66799 [2]
Given Kudos: 436
Location: Pune, India
Re: A train travels at an average speed of 90 km/hr without any stoppages. [#permalink]
2
Kudos
Bunuel wrote:
A train travels at an average speed of 90 km/hr without any stoppages. However, its average speed decrease to 60 km/hr on account of stoppages. On an average, how many minutes per hour does the train stop?

(A) 12 minutes
(B) 18 minutes
(C) 20 minutes
(D) 24 minutes
(E) 30 minutes

In 1 hour, the train travels 90 km (if there are no stoppages).
But in 1 hour, it actually travels only 60 km i.e. 2/3rd of the distance. So actually it runs for only 2/3rd the time i.e. 40 mins. So it stops for 20 min per hour on average.
Non-Human User
Joined: 09 Sep 2013
Posts: 34046
Own Kudos [?]: 853 [0]
Given Kudos: 0
Re: A train travels at an average speed of 90 km/hr without any stoppages. [#permalink]
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.
Re: A train travels at an average speed of 90 km/hr without any stoppages. [#permalink]
Moderator:
Math Expert
94578 posts