How many hours did it take Helen to drive to her parents

Oldest

Best Reply

Author

Message

TAGS:

Intern

Joined: 13 Mar 2006

Posts: 9

Location: Vancouver

Followers: 0

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

How many hours did it take Helen to drive to her parents [#permalink]

03 May 2006, 19:14

00:00

Question Stats:

0% (00:00) correct

0% (00:00) wrong

based on 0 sessions

How many hours did it take Helen to drive to her parents house?

1) her average speed was 72km/h
2) if her average speed was +8km/h it would have taken her 1 hr less

OA is C

Director

Joined: 16 Aug 2005

Posts: 950

Location: France

Followers: 1

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

[#permalink]

03 May 2006, 19:59

speed = distance/time

Let time taken be x hours

1. Not sufficient

2. Not sufficient

Together:
Distance travelled at 72km/h driving for x hours = 72x km

Distance travelled at 80km/h for (x-1) hours = 80(x-1) km

Since distance is same, 72x = 80x - 80
=> 8x = 80 => x=10 hours

Hence Answer is C

Joined: 06 Jun 2004

Posts: 1068

Location: CA

Followers: 2

Kudos [?]: 12 [0], given: 0

[#permalink]

03 May 2006, 21:38

Agree with gmatmba's approach

Also, please do not post the OA in advance so ppl could have a chance to work on it. Tks
_________________

Don't be afraid to take a flying leap of faith.. If you risk nothing, than you gain nothing...

GMAT Club Legend

Joined: 07 Jul 2004

Posts: 5134

Location: Singapore

Followers: 9

Kudos [?]: 87 [0], given: 0

[#permalink]

03 May 2006, 22:04

St1:
We do not know the distance. Insufficient.

St2:
Average speed = s
Distance = d
Time = d/s

If average speed = (s+8)
Time = d/(s+8) = d/s - 1

d/(s+8) = (d-s)/s
ds = (s+8)(d-s)
ds = ds - s^2 + 8d - 8s
s^2 + 8s - 8d = 0

Can't solve as we do not knwo real values of s and d.
Insufficient.

Using St1 and St2:
s^2 + 8s - 8d = 0
75^2 + 8(75) = 8d

Can calculate d and therefore the time taken. Sufficient.

Ans C

[#permalink] 03 May 2006, 22:04

		Similar topics	Author	Replies	Last post
Similar Topics:		How many hours did it take Helen to drive from her house to	djdela	5	23 Jul 2008, 22:50
		How many hours did it take Helen to drive from her house to	bmiller0731	1	03 Feb 2009, 15:54
		How many hours did it take Helen to drive from her house to	changhiskhan	8	26 Mar 2010, 17:00
		How many hours did it take helen to drive from her house to	mydreammba	2	26 Oct 2011, 00:20
	5	How many hours did it take Dale to drive	shrive555	6	20 Dec 2011, 07:47

How many hours did it take Helen to drive to her parents

Main navigation

GMAT Resources

Partners

MBA Resources

GMAT ® is a registered trademark of the Graduate Management Admission Council ® (GMAC ®). GMAT Club's website has not been reviewed or endorsed by GMAC.

GMAT Courses

Admissions Consulting

How many hours did it take Helen to drive to her parents

How many hours did it take Helen to drive to her parents

Main navigation

GMAT Resources

Partners

MBA Resources