NEW HERE? LEARN MORE
closeclose
Last visit was: 25 Apr 2024, 02:46 It is currently 25 Apr 2024, 02:46
Decision Tracker
My Rewards
New posts
New comers' posts

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

A trip of 900 miles would have taken 2 hour less if the average speed

User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92912
Own Kudos [?]: 618889 [0]
Given Kudos: 81595
Send PM
CAT Tests Forum Quiz Mode
A trip of 900 miles would have taken 2 hour less if the average speed [#permalink] New post   26 Sep 2018, 05:02
Expert Reply
00:00
A
B
C
D
E

Difficulty:

95% (hard)

Question Stats:

0% (00:00) correct 100% (03:03) wrong based on 9 sessions
Hide Show timer Statistics
A trip of 900 miles would have taken 2 hour less if the average speed for the trip had been greater by 10 miles per hour. What was the average speed for the trip?

(A) 40 miles per hour
(B) 45 miles per hour
(C) 60 miles per hour
(D) 75 miles per hour
(E) 90 miles per hour

Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Problem Solving (PS) Forum
Still interested in this question? Check out the "Best Topics" block below for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
ShowHide Answer
Official Answer
E
User avatar
L
Mo2men
RSM Erasmus Moderator
Joined: 26 Mar 2013
Posts: 2461
Own Kudos [?]: 1360 [1]
Given Kudos: 641
Concentration: Operations, Strategy
Schools: Erasmus (II)
Send PM
Reviews Badge
Re: A trip of 900 miles would have taken 2 hour less if the average speed [#permalink] New post   27 Sep 2018, 15:57
1
Kudos
Bunuel wrote:
A trip of 900 miles would have taken 2 hour less if the average speed for the trip had been greater by 10 miles per hour. What was the average speed for the trip?

(A) 40 miles per hour
(B) 45 miles per hour
(C) 60 miles per hour
(D) 75 miles per hour
(E) 90 miles per hour


Dear GMATPrepNow

Is the OA correct?

Let v=90...........t=10 hrs...........Total distance =900

If v= 100 (increased by 10)..........t=8 hrs (less by 2 hrs).............Total distance =800 (the total distance must match in both cases which does not happen under the conditions given by the question.

Thanks Brent
User avatar
G
T1101
Manager
Manager
Joined: 07 Aug 2018
Posts: 88
Own Kudos [?]: 251 [1]
Given Kudos: 247
Location: United States (MA)
GMAT 1: 560 Q39 V28
GMAT 2: 670 Q48 V34
Send PM
Re: A trip of 900 miles would have taken 2 hour less if the average speed [#permalink] New post   28 Sep 2018, 08:01
1
Bookmarks
Bunuel wrote:
A trip of 900 miles would have taken 2 hour less if the average speed for the trip had been greater by 10 miles per hour. What was the average speed for the trip?

(A) 40 miles per hour
(B) 45 miles per hour
(C) 60 miles per hour
(D) 75 miles per hour
(E) 90 miles per hour


I agree with Mo2men!

Theere is no correct Answer provided!

In my calculation the time is: 14.454 and the speed: 62.266.... (Only possible with the help of a calculator)
User avatar
L
BrentGMATPrepNow
GMAT Club Legend
GMAT Club Legend
Joined: 12 Sep 2015
Posts: 6821
Own Kudos [?]: 29920 [0]
Given Kudos: 799
Location: Canada
Send PM
Re: A trip of 900 miles would have taken 2 hour less if the average speed [#permalink] New post   28 Sep 2018, 09:48
Expert Reply
Top Contributor
Bunuel wrote:
A trip of 900 miles would have taken 2 hour less if the average speed for the trip had been greater by 10 miles per hour. What was the average speed for the trip?

(A) 40 miles per hour
(B) 45 miles per hour
(C) 60 miles per hour
(D) 75 miles per hour
(E) 90 miles per hour


Let's start with a "word equation"

Travel time at regular speed = Travel time at FASTER speed + 2 hours
Let x = REGULAR speed
So, x + 10 = FASTER speed

Travel time = distance/speed

We get: 900/x = 900/(x + 10)+ 2
Multiply both sides of the equation by x to get: 900 = 900x/(x + 10) + 2x
Multiply both sides of the equation by (x + 10) to get: 900(x + 10) = 900x + 2x(x + 10)
Expand: 900x + 9000 = 900x + 2x² + 20x
Subtract 900x from both sides: 9000 = 2x² + 20x
Subtract 9000 from both sides: 0 = 2x² + 20x - 9000
Divide both sides by 2 to get: 0 = x² + 10x - 4500
Factor to get....hmm, this quadratic equation does not factor nicely (with nice integer solutions, as the 5 answer choices suggest)

Cheers,
Brent
User avatar
P
bebs
Senior Manager
Senior Manager
Joined: 18 Jun 2018
Posts: 334
Own Kudos [?]: 199 [0]
Given Kudos: 1283
Concentration: Finance, Healthcare
Schools: Jones '22 (M$) McCombs '22 (WL) Kelley '22 (A$)
Send PM
Re: A trip of 900 miles would have taken 2 hour less if the average speed [#permalink] New post   28 Sep 2018, 10:02
Bunuel Is there a typo somewhere, especially in the answer choices? All attempts to solve this question made me blank out. Thanks.

Bunuel wrote:
A trip of 900 miles would have taken 2 hour less if the average speed for the trip had been greater by 10 miles per hour. What was the average speed for the trip?

(A) 40 miles per hour
(B) 45 miles per hour
(C) 60 miles per hour
(D) 75 miles per hour
(E) 90 miles per hour


Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Problem Solving (PS) Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
GMAT Club Bot
gmatclubot
Re: A trip of 900 miles would have taken 2 hour less if the average speed [#permalink]
28 Sep 2018, 10:02
Moderators:
Bunuel
Math Expert
92912 posts
yashikaaggarwal
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions