BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

Speed problems

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 256
Joined: Mon Aug 10, 2009 6:31 pm
Thanked: 3 times
by gmatv09 » Thu Dec 17, 2009 8:42 pm
Find out the combined length of the trains if one traveling at 40 km per hour and crosses
another train traveling in same direction at 30 miles per hour in 20 seconds.

a. 150 meters
b. 200 meters
c. 200/3 meters
d. 500/9 meters
e. 100 meters


Raffela walks a certain distance and rides back taking a total time of 50 minutes.
She could walk both ways in 70 minutes. How long would it take him to ride both ways?

a. 40 minutes
b. 100 minutes
c. 120 minutes
d. 25 minutes
e. 30 minutes


A train covers a distance of 20 km in 15 minutes. If its speed is decreased by 20km/hr,
what is the time taken by it to cover the same distance?
a. 10 minutes
b. 15 minutes
c. 20 minutes
d. 40 minutes
e. 80 minutes
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
Master | Next Rank: 500 Posts
Posts: 130
Joined: Sat Dec 29, 2007 5:35 am
Location: SGP
Thanked: 5 times

by satish.nagdev » Fri Dec 18, 2009 12:01 am
for second
say x = walking speed and y be riding speed and d be one side distance

d = s * t so
d/x + d/y = 50 minutes (I)
2d/x=70 so d/x = 35

putting in first d/y + 35 = 50 so one side d/y = 15 which is one side ride hence 30minutes for both ways


in 3rd
20km is covered in 15 minutes so 80km/hr is the speed, this is reduced by 20 that makes it to 60km/hr now to cover 20km at this speed 20 minutes are needed.

1st one is bit confusing :(
Wounded by GMAT but not dead
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Senior | Next Rank: 100 Posts
Posts: 31
Joined: Tue Sep 29, 2009 2:03 pm

by batbond007 » Fri Dec 18, 2009 9:53 am
Ans E i.e 100 meters for the first one.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 130
Joined: Sat Dec 29, 2007 5:35 am
Location: SGP
Thanked: 5 times

by satish.nagdev » Sat Dec 19, 2009 5:25 am
batbond007 wrote:Ans E i.e 100 meters for the first one.
can you explain how did you get that answer?
Wounded by GMAT but not dead
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 416
Joined: Thu Oct 15, 2009 11:52 am
Thanked: 27 times

by regor60 » Mon Dec 21, 2009 7:31 am
Answer for question 1 is "D"

You have a units conflict...30 mph must be 30kph

Same direction > 10 kph relative speed..one train not moving, the other moving at 10 kph

[(10,000 meters/hr)*20 seconds]/ 3600 seconds/hr = 55.55 meters = 500/9 meters
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Senior | Next Rank: 100 Posts
Posts: 84
Joined: Sat Oct 03, 2009 1:13 pm
Thanked: 11 times

by djkvakin » Mon Dec 21, 2009 9:13 am
regor60 wrote:Answer for question 1 is "D"

You have a units conflict...30 mph must be 30kph

Same direction > 10 kph relative speed..one train not moving, the other moving at 10 kph

[(10,000 meters/hr)*20 seconds]/ 3600 seconds/hr = 55.55 meters = 500/9 meters
I agree that the length of the train going 30km/h is 500/9, but the question asks about the combined length of 2 trains. I am not sure how to solve this. Anyone? it doesn't say they have equal length, does it?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1