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

 It is currently 17 Feb 2019, 10:02

### 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

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

## Events & Promotions

###### Events & Promotions in February
PrevNext
SuMoTuWeThFrSa
272829303112
3456789
10111213141516
17181920212223
242526272812
Open Detailed Calendar
• ### Free GMAT Algebra Webinar

February 17, 2019

February 17, 2019

07:00 AM PST

09:00 AM PST

Attend this Free Algebra Webinar and learn how to master Inequalities and Absolute Value problems on GMAT.
• ### Valentine's day SALE is on! 25% off.

February 18, 2019

February 18, 2019

10:00 PM PST

11:00 PM PST

We don’t care what your relationship status this year - we love you just the way you are. AND we want you to crush the GMAT!

# A river boat leaves Silver Town and travels upstream to Gold Town at a

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 52906
A river boat leaves Silver Town and travels upstream to Gold Town at a  [#permalink]

### Show Tags

14 Feb 2016, 03:44
1
5
00:00

Difficulty:

35% (medium)

Question Stats:

72% (01:37) correct 28% (01:37) wrong based on 258 sessions

### HideShow timer Statistics

A river boat leaves Silver Town and travels upstream to Gold Town at an average speed of 6 kilometers per hour. It returns by the same route at an average speed of 9 kilometers per hour. What is the average speed for the round-trip in kilometers per hour?

A) 7.0
B) 7.1
C) 7.2
D) 7.5
E) 8.0

_________________
Intern
Joined: 14 Jan 2016
Posts: 1
Re: A river boat leaves Silver Town and travels upstream to Gold Town at a  [#permalink]

### Show Tags

15 Feb 2016, 09:08
1
Pick a number which is LCM of 9 and 6 = 18.
Upstream time = 18/6 = 3 hrs
Downstream time = 18/9 = 2 hrs
Total time = 5 hrs
Total distance = 36
Average Speed = 36/5 = 7.2 km/hr
VP
Joined: 07 Dec 2014
Posts: 1157
Re: A river boat leaves Silver Town and travels upstream to Gold Town at a  [#permalink]

### Show Tags

15 Feb 2016, 14:22
2
1
let total distance=2d
total time=d/6+d/9=5d/18
2d/(5d/18)=36/5=7.2 km/hr
Current Student
Joined: 21 Jan 2015
Posts: 39
Location: United States
Schools: Booth PT '20
GMAT 1: 660 Q44 V38
GPA: 3.2
Re: A river boat leaves Silver Town and travels upstream to Gold Town at a  [#permalink]

### Show Tags

04 Dec 2016, 19:29
Distances are going to be the same since it is a round-trip. Find an arbitrary value for the distance that can be used by both rates…aka find the multiple. 18 km works.

Then find the hours using D=RT.
18km = (9km/hr)(time) --> 2 hours
18km = (6km/hr)(time) --> 3 hours

Find the total distance and time to get the average speed.
(18km + 18km) / (2 hours + 3 hours) = 36/5 = 7.2 km/hrs

Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 4920
Location: United States (CA)
Re: A river boat leaves Silver Town and travels upstream to Gold Town at a  [#permalink]

### Show Tags

26 Apr 2018, 14:20
Bunuel wrote:
A river boat leaves Silver Town and travels upstream to Gold Town at an average speed of 6 kilometers per hour. It returns by the same route at an average speed of 9 kilometers per hour. What is the average speed for the round-trip in kilometers per hour?

A) 7.0
B) 7.1
C) 7.2
D) 7.5
E) 8.0

We can let the distance = 18, so that the time upstream is 18/6 = 3 hours and the time downstream is 18/9 = 2 hours. Now we can determine average rate.

average rate = total distance/total time

average rate = 36/(3 + 2) = 36/5 = 7.2

_________________

Scott Woodbury-Stewart
Founder and CEO

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Director
Joined: 09 Mar 2018
Posts: 959
Location: India
Re: A river boat leaves Silver Town and travels upstream to Gold Town at a  [#permalink]

### Show Tags

25 Jan 2019, 02:34
Bunuel wrote:
A river boat leaves Silver Town and travels upstream to Gold Town at an average speed of 6 kilometers per hour. It returns by the same route at an average speed of 9 kilometers per hour. What is the average speed for the round-trip in kilometers per hour?

A) 7.0
B) 7.1
C) 7.2
D) 7.5
E) 8.0

Average Speed = 2 a * b/ (a+b)

= 2 * 6 * 9 / 15
= 7.2

C
_________________

If you notice any discrepancy in my reasoning, please let me know. Lets improve together.

Quote which i can relate to.
Many of life's failures happen with people who do not realize how close they were to success when they gave up.

Re: A river boat leaves Silver Town and travels upstream to Gold Town at a   [#permalink] 25 Jan 2019, 02:34
Display posts from previous: Sort by

# A river boat leaves Silver Town and travels upstream to Gold Town at a

 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®.