GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 15 Oct 2018, 23:26

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

A cyclist travels 20 miles at a speed of 15 miles per hour.

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Manager
Manager
avatar
Joined: 15 Apr 2012
Posts: 88
Location: Bangladesh
Concentration: Technology, Entrepreneurship
GMAT 1: 460 Q38 V17
GPA: 3.56
A cyclist travels 20 miles at a speed of 15 miles per hour.  [#permalink]

Show Tags

New post Updated on: 08 Jul 2012, 02:42
1
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

78% (01:39) correct 22% (01:46) wrong based on 275 sessions

HideShow timer Statistics

A cyclist travels 20 miles at a speed of 15 miles per hour. If he returns along the same path and the entire trip takes 2 hours, at what speed did he return?

(A) 15 mph
(B) 20 mph
(C) 22 mph
(D) 30 mph
(E) 34 mph

Originally posted by farukqmul on 08 Jul 2012, 01:58.
Last edited by Bunuel on 08 Jul 2012, 02:42, edited 1 time in total.
Edited the question.
Current Student
User avatar
B
Joined: 29 Mar 2012
Posts: 316
Location: India
GMAT 1: 640 Q50 V26
GMAT 2: 660 Q50 V28
GMAT 3: 730 Q50 V38
GMAT ToolKit User
Re: A cyclist travels 20 miles  [#permalink]

Show Tags

New post 08 Jul 2012, 02:15
3
farukqmul wrote:
A cyclist travels 20 miles at a speed of 15 miles per hour. If he returns along the same path
and the entire trip takes 2 hours, at what speed did he return?
(A) 15 mph (B) 20 mph (C) 22 mph (D) 30 mph (E) 34 mph

Hi,

we know that \(speed = \frac {distance}{time}\)
\(time(2hours) = \frac {20}{15}+\frac {20}{v}\)
or \(v= \frac {20}{2- \frac 43}\)
or \(v= 30\)

Thus, Answer (D)

Regards,
Kaplan GMAT Instructor
User avatar
Joined: 25 Aug 2009
Posts: 635
Location: Cambridge, MA
Re: A cyclist travels 20 miles at a speed of 15 miles per hour.  [#permalink]

Show Tags

New post 08 Jul 2012, 19:05
Cyberjadugar's math is dead on!

There is another way to approach this problem, however--backsolving. Because the answers are numbers in ascending order, and because the task we are assigned is simple (not the same as easy! A speed is simple, the sum of the squares of two speeds would be complex), we can plug those numbers back into the task to see if they work.

With backsolving, it's useful to start at B or D. This maximized our chances of getting the answer right on the first try. If B is too big, or if D is too small, then we immediately know that A or E is correct, respectively.

But B clearly doesn't work here. The total distance traveled is 40 miles, and the total time is two hours. The average speed for the whole trip needs to be 40/2 = 20 mph, so 20 for only the second half won't cut it.

Let's try (D). 20 miles at 15 miles/hour takes 4/3 of an hour. 20 miles at (D) 30 miles/hour takes half that time, 2/3 of an hour. So the whole trip takes 6/3 = 2 hours, just what we wanted!

You may think, "How lucky!" but actually luck played no part. After all, what if we'd been wrong? Well, if we'd spend too little time making the trip, we'd have known that 30 was too fast. Since 20 was too slow, we could have marked (C) as correct without doing a bit of math! And similarly, if we'd been to slow even at 30, we could have just mark (E) and been done. Part of the power of backsolving as a strategy is the ability to use the answer choices as a powerful problem-solving tool.

Good luck on your prep!
_________________

Eli Meyer
Kaplan Teacher
http://www.kaptest.com/GMAT

Prepare with Kaplan and save $150 on a course!

Image

Kaplan Reviews

Veritas Prep GMAT Instructor
User avatar
P
Joined: 16 Oct 2010
Posts: 8374
Location: Pune, India
Re: A cyclist travels 20 miles at a speed of 15 miles per hour.  [#permalink]

Show Tags

New post 08 Jul 2012, 20:47
4
farukqmul wrote:
A cyclist travels 20 miles at a speed of 15 miles per hour. If he returns along the same path and the entire trip takes 2 hours, at what speed did he return?

(A) 15 mph
(B) 20 mph
(C) 22 mph
(D) 30 mph
(E) 34 mph


Let me add another method: Use logic!

He travels 20 miles at a speed of 15 mph so he takes 20/15 = 4/3 hrs to travel one way. Since total time is 2 hrs, he must have taken 2 - 4/3 = 2/3 hrs while returning.
Speed while returning = 20/(2/3) = 30 mph

(It's pretty much what cyberjadugar did but thinking in terms of equations can be a little frustrating during the test.)
_________________

Karishma
Veritas Prep GMAT Instructor

Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >

GMAT self-study has never been more personalized or more fun. Try ORION Free!

Director
Director
User avatar
G
Status: Tutor - BrushMyQuant
Joined: 05 Apr 2011
Posts: 610
Location: India
Concentration: Finance, Marketing
Schools: XLRI (A)
GMAT 1: 700 Q51 V31
GPA: 3
WE: Information Technology (Computer Software)
Re: A cyclist travels 20 miles at a speed of 15 miles per hour.  [#permalink]

Show Tags

New post 19 Jul 2012, 04:16
A cyclist travels 20 miles at a speed of 15 miles per hour

Time taken while going= Distance/Speed = 20/15 hrs = (4/3)hrs

Total time = 2hours

Time taken while returning = total - time taken while going = 2 - 4/3 = (2/3)hrs

Distance = 20miles
Time = (2/3)hrs

Speed = Distance/Time = 20/ (2/3) = 30 miles/hr

So, Answer is D (30mph)

Hope it helps!
_________________

Ankit

Check my Tutoring Site -> Brush My Quant

GMAT Quant Tutor
How to start GMAT preparations?
How to Improve Quant Score?
Gmatclub Topic Tags
Check out my GMAT debrief

How to Solve :
Statistics || Reflection of a line || Remainder Problems || Inequalities

Target Test Prep Representative
User avatar
G
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2830
Re: A cyclist travels 20 miles at a speed of 15 miles per hour.  [#permalink]

Show Tags

New post 19 Apr 2018, 17:29
1
1
farukqmul wrote:
A cyclist travels 20 miles at a speed of 15 miles per hour. If he returns along the same path and the entire trip takes 2 hours, at what speed did he return?

(A) 15 mph
(B) 20 mph
(C) 22 mph
(D) 30 mph
(E) 34 mph


We know that distance/rate = time. If we let the speed of the return trip = r, then our equation for the time for the entire trip is:

time going + time returning = 2 hours

20/15 + 20/r = 2

4/3 + 20/r = 2

Multiplying by 3r, we have:

4r + 60 = 6r

60 = 2r

30 = r

Answer: D
_________________

Jeffery Miller
Head of GMAT Instruction

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

GMAT Club Bot
Re: A cyclist travels 20 miles at a speed of 15 miles per hour. &nbs [#permalink] 19 Apr 2018, 17:29
Display posts from previous: Sort by

A cyclist travels 20 miles at a speed of 15 miles per hour.

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.