Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 44419

A bus traveled from its depot to its destination at an average speed [#permalink]
Show Tags
15 Jul 2015, 03:26
Question Stats:
82% (01:36) correct 18% (01:43) wrong based on 144 sessions
HideShow timer Statistics



Manager
Joined: 14 Sep 2014
Posts: 92
WE: Engineering (Consulting)

Re: A bus traveled from its depot to its destination at an average speed [#permalink]
Show Tags
15 Jul 2015, 03:41
1
This post received KUDOS
Let time for first trip be x hrs
For first trip distance travelled = 60x For round trip distance travelled 40(x+4) = 40x+160
60x = 40x + 160 x = 8 hrs.
Total Round trip distance = 60*8*2 = 960 kilometers



SVP
Joined: 08 Jul 2010
Posts: 2017
Location: India
GMAT: INSIGHT
WE: Education (Education)

Re: A bus traveled from its depot to its destination at an average speed [#permalink]
Show Tags
15 Jul 2015, 05:44
Bunuel wrote: A bus traveled from its depot to its destination at an average speed of 60 kilometers per hour. On its return to the depot along the same route, the bus traveled at an average speed of only 40 kilometers per hour, making the trip 4 hours longer. What is the total distance of the round trip?
A. 360 kilometers B. 400 kilometers C. 600 kilometers D. 800 kilometers E. 960 kilometers
Kudos for a correct solution. The difference of speed (6040 = 20 Kmph) is causing the delay of 4 hours Distance = Speed x Time Case 1: Distance = 60 x T While driving from Depot to Destination Case 2: Distance = 40 x (T+4) While returning from Destination to Depot Since the Distance Travelled is same in both cases therefore 60 x T = 40 x (T+4) i.e. 20 T = 160 i.e. T = 8 Hours i.e. (One side) Distance = 60 x T = 60 x 8 = 480 Total Distance of the round trip = 480 x 2 = 960 Km Answer: Option E
_________________
Prosper!!! GMATinsight Bhoopendra Singh and Dr.Sushma Jha email: info@GMATinsight.com I Call us : +919999687183 / 9891333772 Online OneonOne Skype based classes and Classroom Coaching in South and West Delhi http://www.GMATinsight.com/testimonials.html
22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION



Senior Manager
Joined: 28 Jun 2015
Posts: 298
Concentration: Finance
GPA: 3.5

Re: A bus traveled from its depot to its destination at an average speed [#permalink]
Show Tags
15 Jul 2015, 05:57
1
This post received KUDOS
Let the distance be D km and T be time taken (in hours). Now, D/60 = T; D/40 = T+4 D/60  D/40 = 4 D(4060/2400) = 4 D(20/2400) = 4 D = 480 km So, total distance = 960 km. Ans (E).
_________________
I used to think the brain was the most important organ. Then I thought, look what’s telling me that.



Manager
Status: Helping People Ace the GMAT
Affiliations: GMAT Answers
Joined: 16 Jan 2013
Posts: 184
Location: United States
Concentration: Finance, Entrepreneurship
GPA: 3.1
WE: Consulting (Consulting)

Re: A bus traveled from its depot to its destination at an average speed [#permalink]
Show Tags
15 Jul 2015, 06:07
1
This post received KUDOS
1
This post was BOOKMARKED
Think about the concepts. The distance for the 2 trips is the same. So if RT = D, then R 1T 1 = R 2T 2. You can now plug in the infromation: 60T = 40 (T + 4). Solving T = 8 If the time for the first half took 8 hours and the speed was 60km/hour 8 x 60 = 480. The total distance is then 480 + 480.
_________________
Want to Ace the GMAT with 1 button? Start Here: GMAT Answers is an adaptive learning platform that will help you understand exactly what you need to do to get the score that you want.



SVP
Joined: 08 Jul 2010
Posts: 2017
Location: India
GMAT: INSIGHT
WE: Education (Education)

Re: A bus traveled from its depot to its destination at an average speed [#permalink]
Show Tags
15 Jul 2015, 06:27
Bunuel wrote: A bus traveled from its depot to its destination at an average speed of 60 kilometers per hour. On its return to the depot along the same route, the bus traveled at an average speed of only 40 kilometers per hour, making the trip 4 hours longer. What is the total distance of the round trip?
A. 360 kilometers B. 400 kilometers C. 600 kilometers D. 800 kilometers E. 960 kilometers
Kudos for a correct solution. ALTERNATE METHODSpeed reduces from 60 to 40 during return journey i.e. New Speed while return (40) = (2/3)*60 But Distance = Speed x Time But if Distance is multiplied with some factor (2/3 in this case) then Time should be multiplied with reciprocal of that factor (2/3 in this case) i.e. Distance = (2/3)Speed x (3/2)Timei.e. Time during return should be (3/2) of previous time i.e. If Old Time = T then, New Time during return = (3/2)T and (3/2)T  T = 4 Hoursi.e. T = 8 Hours i.e. (One side) Distance = 60x8 or 40x12 = 480 Both ways Distance = 480*2 = 960 Answer: Option E
_________________
Prosper!!! GMATinsight Bhoopendra Singh and Dr.Sushma Jha email: info@GMATinsight.com I Call us : +919999687183 / 9891333772 Online OneonOne Skype based classes and Classroom Coaching in South and West Delhi http://www.GMATinsight.com/testimonials.html
22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION



Veritas Prep GMAT Instructor
Joined: 15 Jul 2015
Posts: 111
GPA: 3.62
WE: Corporate Finance (Consulting)

Re: A bus traveled from its depot to its destination at an average speed [#permalink]
Show Tags
15 Jul 2015, 11:31
One way to think about this is that the Distance of the two trips is same. Thus, 40t + 4 hours = 60t. Further, since t will be the same on each side of the equation, you can subtract 40t from each side. That leaves you with 4 hours at 40kph, or 160 km = 20t, or t=8 hours. Finally, since the question asks for the distance of the roundtrip, you can find this by 60 x 8 x 2, or 960 km.
_________________
Dennis Veritas Prep  GMAT Instructor
Get started with Veritas Prep GMAT On Demand for $199
Veritas Prep Reviews



Intern
Joined: 04 Nov 2013
Posts: 43
Concentration: Finance, Strategy
GPA: 4

Re: A bus traveled from its depot to its destination at an average speed [#permalink]
Show Tags
15 Jul 2015, 20:56
1
This post received KUDOS
Bunuel wrote: A bus traveled from its depot to its destination at an average speed of 60 kilometers per hour. On its return to the depot along the same route, the bus traveled at an average speed of only 40 kilometers per hour, making the trip 4 hours longer. What is the total distance of the round trip?
A. 360 kilometers B. 400 kilometers C. 600 kilometers D. 800 kilometers E. 960 kilometers
Kudos for a correct solution. Distance = Speed x Time Trip 1: D = 60(x) Trip 2: D = 40(x+40) In round trip problems, the distances are the same. 60x=40(x+40) 60x=40x+160 20x=160 x=8 D = 60(8) D=480 480(2) = 960 km round trip.
_________________
Please kudos if you found this post helpful. I am trying to unlock the tests



Intern
Joined: 11 Sep 2013
Posts: 7

Re: A bus traveled from its depot to its destination at an average speed [#permalink]
Show Tags
15 Jul 2015, 22:52
1
This post received KUDOS
Speed*time=distance Let time for trip one be x Trip1 d1= 60*x Trip2 d2= 40*(x+4) D1=D2 So x= 8 So d1= 480 d2= 480 Total distance =960 kms E



Intern
Joined: 22 Dec 2014
Posts: 43

Re: A bus traveled from its depot to its destination at an average speed [#permalink]
Show Tags
17 Jul 2015, 03:29
1
This post received KUDOS
Bunuel wrote: A bus traveled from its depot to its destination at an average speed of 60 kilometers per hour. On its return to the depot along the same route, the bus traveled at an average speed of only 40 kilometers per hour, making the trip 4 hours longer. What is the total distance of the round trip?
A. 360 kilometers B. 400 kilometers C. 600 kilometers D. 800 kilometers E. 960 kilometers
Kudos for a correct solution. Time for bus to travel its route at average speed of 60kph: t Given the information, we have equation: \(60t=40(t+4)\) > \(t=8\)(hrs) > total distance of the round trip \(=60*8*2=960\)(km) Answer E



Director
Joined: 21 May 2013
Posts: 618

Re: A bus traveled from its depot to its destination at an average speed [#permalink]
Show Tags
17 Jul 2015, 11:39
Bunuel wrote: A bus traveled from its depot to its destination at an average speed of 60 kilometers per hour. On its return to the depot along the same route, the bus traveled at an average speed of only 40 kilometers per hour, making the trip 4 hours longer. What is the total distance of the round trip?
A. 360 kilometers B. 400 kilometers C. 600 kilometers D. 800 kilometers E. 960 kilometers
Kudos for a correct solution. Let one way distance=d Now, d/60+4=d/40 d/40d/60=4 3d2d/120=4 d=480 2d=960 km Answer E



Manager
Joined: 20 Jul 2011
Posts: 81

Re: A bus traveled from its depot to its destination at an average speed [#permalink]
Show Tags
17 Jul 2015, 16:38
Bunuel wrote: A bus traveled from its depot to its destination at an average speed of 60 kilometers per hour. On its return to the depot along the same route, the bus traveled at an average speed of only 40 kilometers per hour, making the trip 4 hours longer. What is the total distance of the round trip?
A. 360 kilometers B. 400 kilometers C. 600 kilometers D. 800 kilometers E. 960 kilometers
Kudos for a correct solution. Two ways to solve this qn: (Maybe many ways) 1. Distance traveled is same in to and fro problems 60 * t = 40 * (t + 4) => Solving for t, t = 8 Distance = 8*60 = 480 (Usually this will be the trap answer). But they have asked for round trip distance. hence 2*D = 960. Option E 2. Time Difference btw the two trips is 4 hours. This difference is bec of difference in speed. Hence, T2  T1 =4 D/40  D/60 = 4 Solving for D, D=> 480; 2D => 960. Option E Would like to know if there are any standard techniques that can be applied to all Time/Distance/Speed problems. Thanks



Math Expert
Joined: 02 Sep 2009
Posts: 44419

Re: A bus traveled from its depot to its destination at an average speed [#permalink]
Show Tags
19 Jul 2015, 13:04
Bunuel wrote: A bus traveled from its depot to its destination at an average speed of 60 kilometers per hour. On its return to the depot along the same route, the bus traveled at an average speed of only 40 kilometers per hour, making the trip 4 hours longer. What is the total distance of the round trip?
A. 360 kilometers B. 400 kilometers C. 600 kilometers D. 800 kilometers E. 960 kilometers
Kudos for a correct solution. 800score Official Solution:The distance formula is Distance = Rate × Time. To solve this question, set x as the length of time (in hours) for the first trip. The distance to the destination city is 60 × x, where rate = 60 and time = x. The return trip was 4 hours longer, so its distance is 40(x + 4). Since we know the distances are the same, we can set them equal to each other and solve for x: 60x = 40(x + 4) 60x = 40x + 160 20x = 160 x = 8. So, the trip took 8 hours, and its distance is 8 × 60 = 480 kilometers. The question asks for the roundtrip distance, so we double the length of the oneway trip: 480 × 2 = 960 kilometers. The correct answer is choice (E).
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



NonHuman User
Joined: 09 Sep 2013
Posts: 6542

Re: A bus traveled from its depot to its destination at an average speed [#permalink]
Show Tags
22 Sep 2017, 06:18
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 Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources




Re: A bus traveled from its depot to its destination at an average speed
[#permalink]
22 Sep 2017, 06:18






