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

It is currently 16 Aug 2018, 05:10

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 boat traveled upstream a distance of 90 miles at an

  post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Current Student
avatar
Joined: 06 Sep 2005
Posts: 49
A boat traveled upstream a distance of 90 miles at an  [#permalink]

Show Tags

New post Updated on: 10 Feb 2014, 13:34
7
40
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

75% (01:55) correct 25% (02:01) wrong based on 507 sessions

HideShow timer Statistics

A boat traveled upstream 90 miles at an average speed of (v-3) miles per hour and then traveled the same distance downstream at an average speed of (v+3) miles per hour. If the trip upstream took a half hour longer than the trip downstream, then how many hours did it take the boat to travel downstream?

A. 2.5
B. 2.4
C. 2.3
D. 2.2
E. 2.1

OPEN DISCUSSION OF THIS QUESTION IS HERE: a-boat-traveled-upstream-90-miles-at-an-average-speed-of-100767.html

Originally posted by CfaMiami on 23 Jul 2006, 09:02.
Last edited by Bunuel on 10 Feb 2014, 13:34, edited 1 time in total.
Edited the question and added the OA.
Manager
Manager
User avatar
Joined: 02 Apr 2006
Posts: 154
  [#permalink]

Show Tags

New post 23 Jul 2006, 09:41
2
2
90/(V-3) = 90/(V+3) + 0.5 hours
=> 90(V+3) = (V-3) [90 + 0.5 V + 1.5]

90V + 270 = (V-3)(183/2 + V/2)
180V + 540 = (V-3)(183+V)= 183V- 549+ V^2 -3V

V^2 - 1089= 0 => V= 33 miles/hr

=> Time downstream = 90/36 = 30/12= 5/2= 2.5 hrs
Director
Director
User avatar
Joined: 28 Dec 2005
Posts: 727
  [#permalink]

Show Tags

New post 23 Jul 2006, 14:11
90/(v-3)=0.5+90/(v+3)

solve for v=33
Then, Td=90/36=2.5

A
SVP
SVP
avatar
Joined: 30 Mar 2006
Posts: 1699
  [#permalink]

Show Tags

New post 26 Jul 2006, 02:39
3
2
A

Time taken upstream = 90/v-3
Time taken downstream = 90/v+3

Hence

90/v-3 + 90/v+3 = 1/2

v = 33

Time taken downstream = 90/36 = 5/2 = 2.5 hrs
Intern
Intern
avatar
Joined: 17 Jan 2010
Posts: 26
Re: GMAT PREP PS Boat (Upstream vs Downstream)  [#permalink]

Show Tags

New post 24 Jan 2010, 03:51
it took me a while, but i finally got it :)
Manager
Manager
User avatar
Joined: 22 Jan 2010
Posts: 110
Schools: UCLA, INSEAD
Re: GMAT PREP PS Boat (Upstream vs Downstream)  [#permalink]

Show Tags

New post 24 Jan 2010, 09:50
I forgot to take account for both directions. I add the current on one but forgot to subtract it from the other.
Intern
Intern
avatar
Joined: 09 Jul 2009
Posts: 49
Location: Bangalore
Schools: ISB
Re: GMAT PREP PS Boat (Upstream vs Downstream)  [#permalink]

Show Tags

New post 21 Oct 2011, 11:00
2
http://www.beatthegmat.com/boat-traveled-t18353.html
Beautiful solution
_________________

The only way of finding the limits of the possible is by going beyond them into the impossible.

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 47923
Re: A boat traveled upstream a distance of 90 miles at an  [#permalink]

Show Tags

New post 10 Feb 2014, 13:34
7
15
A boat traveled upstream 90 miles at an average speed of (v-3) miles per hour and then traveled the same distance downstream at an average speed of (v+3) miles per hour. If the trip upstream took a half hour longer than the trip downstream, then how many hours did it take the boat to travel downstream?

A. 2.5
B. 2.4
C. 2.3
D. 2.2
E. 2.1

Trip upstream took \(\frac{90}{v-3}\) hours and trip downstream took \(\frac{90}{v+3}\) hours. Also given that the difference in times was \(\frac{1}{2}\) hours --> \(\frac{90}{v-3}-\frac{90}{v+3}=\frac{1}{2}\);

\(\frac{90}{v-3}-\frac{90}{v+3}=\frac{1}{2}\) --> \(\frac{90(v+3)-90(v-3)}{v^2-9}=\frac{1}{2}\) --> \(\frac{90*6}{v^2-9}=\frac{1}{2}\) --> \(v^2=90*6*2+9\) --> \(v^2=9*(10*6*2+1)\) --> \(v^2=9*121\) --> \(v=3*11=33\);

Trip downstream took \(\frac{90}{v+3}=\frac{90}{33+3}=2.5\) hours.

Answer: A.

OPEN DISCUSSION OF THIS QUESTION IS HERE: a-boat-traveled-upstream-90-miles-at-an-average-speed-of-100767.html
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Veritas Prep GMAT Instructor
User avatar
P
Joined: 16 Oct 2010
Posts: 8187
Location: Pune, India
Re: A boat traveled upstream a distance of 90 miles at an  [#permalink]

Show Tags

New post 10 Feb 2014, 22:12
3
1
CfaMiami wrote:
A boat traveled upstream 90 miles at an average speed of (v-3) miles per hour and then traveled the same distance downstream at an average speed of (v+3) miles per hour. If the trip upstream took a half hour longer than the trip downstream, then how many hours did it take the boat to travel downstream?

A. 2.5
B. 2.4
C. 2.3
D. 2.2
E. 2.1

OPEN DISCUSSION OF THIS QUESTION IS HERE: a-boat-traveled-upstream-90-miles-at-an-average-speed-of-100767.html


Here is a post discussing how to solve such equations easily: http://www.veritasprep.com/blog/2013/03 ... culations/
_________________

Karishma
Veritas Prep GMAT Instructor

Save up to $1,000 on GMAT prep through 8/20! Learn more here >

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

Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 7719
Premium Member
Re: A boat traveled upstream a distance of 90 miles at an  [#permalink]

Show Tags

New post 26 Jul 2018, 12:17
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Re: A boat traveled upstream a distance of 90 miles at an &nbs [#permalink] 26 Jul 2018, 12:17
Display posts from previous: Sort by

A boat traveled upstream a distance of 90 miles at an

  post reply Question banks Downloads My Bookmarks Reviews Important topics  

Events & Promotions

PREV
NEXT


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®.