Find all School-related info fast with the new School-Specific MBA Forum

It is currently 29 Aug 2014, 02:14

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

How many hours did it take Helen to drive from her house to

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
avatar
Joined: 16 Jul 2008
Posts: 16
Followers: 0

Kudos [?]: 1 [0], given: 0

How many hours did it take Helen to drive from her house to [#permalink] New post 23 Jul 2008, 21:50
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

78% (01:42) correct 22% (00:41) wrong based on 64 sessions
How many hours did it take Helen to drive from her house to her parent's house?

(1) Helen's average speed on this trip was 72 kilometers per hour
(2) If Helen's average speed on this trip had been 8 kilometers per hour greater , it would have taken her 1 hour less.

OPEN DISCUSSION OF THIS QUESTION IS HERE: how-many-hours-did-it-take-helen-to-drive-from-her-house-to-91891.html
[Reveal] Spoiler: OA

Last edited by Bunuel on 30 Aug 2013, 03:08, edited 1 time in total.
Moved to DS forum and added the OA.
Kaplan GMAT Prep Discount CodesKnewton GMAT Discount CodesManhattan GMAT Discount Codes
Manager
Manager
avatar
Joined: 03 Jun 2008
Posts: 136
Schools: ISB, Tuck, Michigan (Ross), Darden, MBS
Followers: 1

Kudos [?]: 7 [0], given: 0

Re: Complex rate problem [#permalink] New post 23 Jul 2008, 21:58
Statement 1: Alone is insufficient as distance is unavailable.

Statement 2: Alone is insufficient as neither speed nor distance is available.

Combining Both: From Statement 1 we know that 72 km/hr is the avg. speed. Let the time taken by helen be X.

Thereforhome.e distance travelled by Helen is 72*X

From statement 2, we know that if the speed had been 8 km/hr more than the original it would take 1 hr less.

=> 72X/80 = X-1

Therefore we can solve for X, which is the time take by Helen.
_________________

-----------------------------------------------------------
'It's not the ride, it's the rider'

Manager
Manager
avatar
Joined: 14 Jun 2008
Posts: 161
Followers: 1

Kudos [?]: 18 [0], given: 0

Re: Complex rate problem [#permalink] New post 24 Jul 2008, 02:55
(1) cannot say anything

Let x = time taken in 72 km / hr case

since distance = speed * time

72x = (72 + 8) (x -1)
72x = 80(x - 1)
8x = 80
x = 10

so (2) sufficient

so B
Current Student
avatar
Joined: 28 Dec 2004
Posts: 3405
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 13

Kudos [?]: 158 [0], given: 2

GMAT Tests User
Re: Complex rate problem [#permalink] New post 24 Jul 2008, 03:05
djdela wrote:
How many hours did it take Helen to drive from her house to her parent's house?

(1) Helen's average speed on this trip was 72 kilometers per hour
(2) If Helen's average speed on this trip had been 8 kilometers per hour greater , it would have taken her 1 hour less.


i suck at Q..what can i say..

D/V=t

D/(v+8)=t+1

Vt=(t+1)(v+8)
vt+8t+v=vt

8t+v=0...we dont know V and and t..

1) we are told v=72

1+2) 8t=72 t=9

i get C..
Manager
Manager
avatar
Joined: 14 Jun 2008
Posts: 161
Followers: 1

Kudos [?]: 18 [0], given: 0

Re: Complex rate problem [#permalink] New post 24 Jul 2008, 03:10
sset009 wrote:
(1) cannot say anything

Let x = time taken in 72 km / hr case

since distance = speed * time

72x = (72 + 8) (x -1)
72x = 80(x - 1)
8x = 80
x = 10

so (2) sufficient

so B

oops used, info from 1
should be C
Senior Manager
Senior Manager
User avatar
Joined: 19 Mar 2008
Posts: 354
Followers: 1

Kudos [?]: 15 [0], given: 0

GMAT Tests User
Re: Complex rate problem [#permalink] New post 24 Jul 2008, 07:45
How many hours did it take Helen to drive from her house to her parent's house?

(1) Helen's average speed on this trip was 72 kilometers per hour
(2) If Helen's average speed on this trip had been 8 kilometers per hour greater , it would have taken her 1 hour less.


(1) alone is NOT sufficient. it just gives speed, no information on time and distance.

(2) alone is NOT sufficient. We can derive a relationship: (let x be speed, t = time)
x*t = (x+8)*(t-1)

(1) +(2), then 72t = 80(t-1)
Sufficient

Ans is C
Manager
Manager
avatar
Joined: 07 May 2013
Posts: 109
Followers: 0

Kudos [?]: 8 [0], given: 1

Re: How many hours did it take Helen to drive from her house to [#permalink] New post 29 Aug 2013, 20:01
D/72-D/80=1
solve for D. we get D=720
COMBINE . answer is C.
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 22146
Followers: 3412

Kudos [?]: 24976 [0], given: 2698

Re: How many hours did it take Helen to drive from her house to [#permalink] New post 30 Aug 2013, 03:08
Expert's post
Re: How many hours did it take Helen to drive from her house to   [#permalink] 30 Aug 2013, 03:08
    Similar topics Author Replies Last post
Similar
Topics:
11 Experts publish their posts in the topic How many hours did it take Dale to drive shrive555 7 20 Dec 2011, 06:47
How many hours did it take helen to drive from her house to mydreammba 2 25 Oct 2011, 23:20
1 Experts publish their posts in the topic How many hours did it take Helen to drive from her house to changhiskhan 9 26 Mar 2010, 16:00
How many hours did it take Helen to drive from her house to bmiller0731 1 03 Feb 2009, 14:54
How many hours did it take Helen to drive to her parents sideslip 3 03 May 2006, 18:14
Display posts from previous: Sort by

How many hours did it take Helen to drive from her house to

  Question banks Downloads My Bookmarks Reviews Important topics  


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

Powered by phpBB © phpBB Group and phpBB SEO

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®.