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

It is currently 20 Apr 2019, 09:43

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 car averages 55 mph for the first 4 hours of a trip and averages 70

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

Hide Tags

 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 54376
A car averages 55 mph for the first 4 hours of a trip and averages 70  [#permalink]

Show Tags

New post 02 Nov 2015, 08:51
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

89% (01:43) correct 11% (02:46) wrong based on 163 sessions

HideShow timer Statistics

Verbal Forum Moderator
User avatar
V
Status: Greatness begins beyond your comfort zone
Joined: 08 Dec 2013
Posts: 2250
Location: India
Concentration: General Management, Strategy
Schools: Kelley '20, ISB '19
GPA: 3.2
WE: Information Technology (Consulting)
GMAT ToolKit User Reviews Badge CAT Tests
Re: A car averages 55 mph for the first 4 hours of a trip and averages 70  [#permalink]

Show Tags

New post 02 Nov 2015, 09:04
2
Let the time for which car averages 70 mph = t

60*(t+4)= 55*4 + 70 t
=>10 t= 20
=> t = 2

Total duration of the trip = 4+2=6

Answer A
_________________
When everything seems to be going against you, remember that the airplane takes off against the wind, not with it. - Henry Ford
The Moment You Think About Giving Up, Think Of The Reason Why You Held On So Long
+1 Kudos if you find this post helpful
Current Student
avatar
Joined: 02 Jun 2015
Posts: 78
Location: Brazil
Concentration: Entrepreneurship, General Management
GPA: 3.3
Re: A car averages 55 mph for the first 4 hours of a trip and averages 70  [#permalink]

Show Tags

New post 02 Nov 2015, 09:44
(4*55) + 70x / x + 4 = 60
220 + 70x = 60x + 240
10x = 20
x = 2

4 initial hours + 2 hours = 6 hours
Director
Director
User avatar
G
Joined: 20 Feb 2015
Posts: 795
Concentration: Strategy, General Management
Premium Member
Re: A car averages 55 mph for the first 4 hours of a trip and averages 70  [#permalink]

Show Tags

New post 23 Nov 2015, 00:29
Let x be the distance travelled at the speed of 70 mph

(4*55+70*x)/4+x=60
220+70x=240+60x
10x=20
x=2

Total distance =4+2=6
Board of Directors
User avatar
P
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4419
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
GMAT ToolKit User CAT Tests
Re: A car averages 55 mph for the first 4 hours of a trip and averages 70  [#permalink]

Show Tags

New post 23 Nov 2015, 09:02
Bunuel wrote:
A car averages 55 mph for the first 4 hours of a trip and averages 70 mph for each additional hour. The average speed for the entire trip was 60 mph. How many hours long is the trip?

A. 6
B. 8
C. 11
D. 12
E. 14


Distance travelled by the car in the first 4 hours is 55*4 = 220 miles

Let the time the car travelled after the first 4 hours be "t"

The total distance covered by the car in " t + 4 " hours is 220 + 70t = 60 ( t + 4)

Or, 220 + 70t = 60t + 240
Or, 10t = 20
Or, t = 2

So the time travelled by the car after the initial 4 hour is 2 hours.


Total time taken by the car is 4 + 2 = 6 Hours.
_________________
Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )
Intern
Intern
avatar
Joined: 15 Sep 2015
Posts: 8
Re: A car averages 55 mph for the first 4 hours of a trip and averages 70  [#permalink]

Show Tags

New post 02 Dec 2015, 07:10
We can use the weighted average approach here, and we know we want total time. Which is just T= T1 + T2

Since we are given average rate at 60mph, which indicates that T1 is larger than T2, since R1 is only 5 away from the average, while R2 is 10 away.

T1=4 hours
R1 = 55 mph
T2=?
R2= 70 mph


(T1*R1 + T2*R2)/(T1+T2) = Tavg

Which is:
T1*R1 + T2*R2= T1*Tavg + T2*Tavg

T1*R1 - T1*Tavg = T2*avg - T2*R2

T1*(R1 - Tavg)= T2*(Tavg - R2)

T1/T2 = (Tavg - R2) / (R1 - Tavg)

Plugging in Values

4/T2 = (60-70) / (55 - 60)

4/T2 = -10 / - 5

4/T2 = 2

T2=2

T = T1 + T2
T = 4 + 2
T = 6
CEO
CEO
User avatar
D
Status: GMATINSIGHT Tutor
Joined: 08 Jul 2010
Posts: 2906
Location: India
GMAT: INSIGHT
Schools: Darden '21
WE: Education (Education)
Reviews Badge
Re: A car averages 55 mph for the first 4 hours of a trip and averages 70  [#permalink]

Show Tags

New post 02 Dec 2015, 07:21
Bunuel wrote:
A car averages 55 mph for the first 4 hours of a trip and averages 70 mph for each additional hour. The average speed for the entire trip was 60 mph. How many hours long is the trip?

A. 6
B. 8
C. 11
D. 12
E. 14


Distance travelled in first 4 hours = 55*4 = 220 miles

Let, remaining Time = t

i.e. Remaining Distance = 70*t

Total Distance = 60*(4+t)

i.e. 60*(4+t) = 220+70t

i.e. 240+60t = 220+70t
i.e. t = 2

i.e. Total Distance = 60*(4+t) = 60*(4+2) = 360
Total Time = 4+2 = 6 hours

Answer: option A
_________________
Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION
Intern
Intern
avatar
B
Joined: 04 Aug 2017
Posts: 10
A car averages 55 mph for the first 4 hours of a trip and averages 70  [#permalink]

Show Tags

New post 05 Aug 2017, 00:58
by deduction (without using calculation), we should be able to establish that the number will be closer to the 4hr++ mark as avg speed of both was 60mph (ie closer to 55mph than 70mph) - 6hrs to be the most "reasonable" option.

please correct me if this is not reasonable.
Target Test Prep Representative
User avatar
G
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2825
Re: A car averages 55 mph for the first 4 hours of a trip and averages 70  [#permalink]

Show Tags

New post 09 Aug 2017, 12:50
Bunuel wrote:
A car averages 55 mph for the first 4 hours of a trip and averages 70 mph for each additional hour. The average speed for the entire trip was 60 mph. How many hours long is the trip?

A. 6
B. 8
C. 11
D. 12
E. 14


We can let the time for the remainder of the trip = t, and thus:

average speed = (distance 1 + distance 2)/(time 1 + time 2)

60 = (55 x 4 + 70t)/(4 + t)

60(4 + t) = 220 + 70t

240 + 60t = 220 + 70t

20 = 10t

t = 2

Thus, the trip was 4 + 2 = 6 hours.

Answer: A
_________________

Jeffrey Miller

Head of GMAT Instruction

Jeff@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

GMAT Club Bot
Re: A car averages 55 mph for the first 4 hours of a trip and averages 70   [#permalink] 09 Aug 2017, 12:50
Display posts from previous: Sort by

A car averages 55 mph for the first 4 hours of a trip and averages 70

  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®.