by: sayakbhatt
8 mins
|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
74% (02:08) correct
26%
(02:10)
wrong
based on 1778
sessions
History
Date
Time
Result
Not Attempted Yet
Triathlete Dan runs along a 2-mile stretch of river and then swims back along the same route. If Dan runs at a rate of 10 miles per hour and swims at a rate of 6 miles per hour, what is his average rate for the entire trip in miles per minute?
A. 1/8
B. 2/15
C. 3/15
D. 1/4
E. 3/8
A. 1/8
B. 2/15
C. 3/15
D. 1/4
E. 3/8
Dan travels 4 miles round trip.
Running part: (2/10 = 1/5*60 = 12 minutes)
Swimming Part: (2/6 = 1/3*60 = 20 minutes)
4 miles in (12+20) minutes
4/32 = 1/8 mile per minute
Answer: 1/8 mile per minute
Running part: (2/10 = 1/5*60 = 12 minutes)
Swimming Part: (2/6 = 1/3*60 = 20 minutes)
4 miles in (12+20) minutes
4/32 = 1/8 mile per minute
Answer: 1/8 mile per minute
If distance traveled is same but at varying rates, the average rate can be found through the shortcut \(\frac{2ab}{a+b}\) where a and b are individual rates.
In this problem \(a=10\) and \(b=6\) therefore average speed = \(\frac{15}{2}\) miles per hour, i.e. \(\frac{1}{8}\) miles per minute.
P.S. Added tags as saw this question in an MGMAT CAT.
In this problem \(a=10\) and \(b=6\) therefore average speed = \(\frac{15}{2}\) miles per hour, i.e. \(\frac{1}{8}\) miles per minute.
P.S. Added tags as saw this question in an MGMAT CAT.
General Discussion
dynamo
Total Distance/Total time
=4/ [( 1/5) + (1/3)]= 15/2
in miles per minute 15/2*60 = 1/8
time to run = 1/5 hr = 12 minutes
time to swim = 1/3 hr = 20 minutes
average rate = total distance / total time
= 4 miles / 20+12 = 4/32 = 1/8 mile per minute
time to swim = 1/3 hr = 20 minutes
average rate = total distance / total time
= 4 miles / 20+12 = 4/32 = 1/8 mile per minute
PareshGmat
Joined: 27 Dec 2012
Last visit: 10 Jul 2016
Posts: 1,531
Status:The Best Or Nothing
Location: India
Concentration: General Management, Technology
WE:Information Technology (Computer Software)
Posts: 1,531
Dienekes
Can you kindly update OA for this?
Thanks
Posts: 122
dynamo
t1 = 2/10 hours
t2 = 2/6
t =t1 + t2 = 2/10 + 2/6 = 16/30
Average speed = Total distance/ total time = 4/ [16/30] = 15/2 mph
15/2 * 1/60 = 1/8 miles/min
Ans.: A
dynamo
We can approach this problem using conversion factors
If the total distance is 2 miles and Dan runs at a rate of 10 miles per hour then he will cover in 1/5 of an hour or 1 mile in 6 minutes
1 mile/6 minutes = 2 miles/ 20 minutes
cross multiply add and then divide by 2
(16 miles /2) / 60 minutes
(16 miles/2)/ 1 minute
8 miles/ 1 minute
1 minute/ 8 miles
Dienekes
Thank you for the explanation. I picked answer choice "B" because I did not pay attention to the unit (minutes) in the question.
Posts: 6,727
dynamo
Average speed = (total distance)/(total time)
We know the total distance = 4 miles
The total time consists of two parts:
Let's begin with a "word equation"
TOTAL time = (time spent running) + (time spent swimming)
time = distance/speed
So, time spent running = 2/10 = 1/5 hours = 12 minutes
time spent swimming = 2/6 = 1/3 hours = 20 minutes
TOTAL time = (12 minutes) + (20 minutes)
= 32 minutes
AVERAGE speed = (total distance)/(total time)
= (4 miles)/(32 minutes)
= 1/8 miles/minute
Answer: A
Cheers,
Brent
JeffTargetTestPrep
Expert
Target Test Prep Representative
Joined: 04 Mar 2011
Last visit: 05 Jan 2024
Posts: 2,973
Status:Head GMAT Instructor
Affiliations: Target Test Prep
Expert reply
Posts: 2,973
dynamo
We can use the average rate formula: average = total distance/total time. We see that the total distance is 4 miles. The total time for swimming is (2 miles)/(6 miles per hour) , and the total time for running is (2 miles)/(10 miles per hour). Thus, we have:
average = 4/(2/6 + 2/10)
average = 4/(1/3 + 1/5)
average = 4/(5/15 + 3/15)
average = 4/(8/15) = 60/8 mph
Since 1 hour = 60 minutes, then 60/8 mph = 60 mi/8 hr x 1 hr/60 min = 1/8 mi/min.
Answer: A
_________________
Jeffrey Miller | Head of GMAT Instruction |
[email protected]
See why Target Test Prep is the top rated GMAT course on GMAT Club. Read Our Reviews
dynamo
Avg. Speed when distance for two trips is same = \(\frac{2 * R1 * R2}{R1 + R2}\)
Avg. spee = 2 * 10 * 6/10 + 6
= 120/16
= 15/2 miles / hr
= 15/2 * 1/60 miles / minute
= 1/8
Hence (A)
_________________
"Do not watch clock; Do what it does. KEEP GOING."
dynamo
\({\text{2}}\,{\text{miles}}\,\,\,\,({\text{go}}\,\,{\text{and}}\,\,{\text{back}})\)
\({V_{{\text{run}}}} = \frac{{10\,\,{\text{miles}}}}{{1\,\,{\text{h}}}}\,\,\,\,\,\,;\,\,\,\,\,{V_{{\text{swim}}}} = \frac{{6\,\,{\text{miles}}}}{{1\,\,{\text{h}}}}\)
\(?\,\,:\,\,\,\,\frac{{{\text{total}}\,\,{\text{miles}}}}{{{\text{total}}\,\,{\text{minutes}}}} = \frac{{4\,\,{\text{miles}}}}{{?{\,_{{\text{temporary}}\,\,{\text{focus}}}}}}\)
Excellent opportunity to use UNITS CONTROL, one of the most powerful tools of our method!
\(\left. \begin{gathered}\\
{\text{Run}}:\,\,\,2\,{\text{miles}}\,\,\left( {\frac{{1\,\,{\text{h}}}}{{10\,\,{\text{miles}}}}\,\,\begin{array}{*{20}{c}}\\
\nearrow \\ \\
\nearrow \\
\end{array}} \right)\,\,\left( {\frac{{60\,\,{\text{minutes}}}}{{1\,\,h}}\,\,\begin{array}{*{20}{c}}\\
\nearrow \\ \\
\nearrow \\
\end{array}} \right)\,\,\, = \,\,12\,\,{\text{minutes}} \hfill \\\\
{\text{Swim}}:\,\,\,2\,{\text{miles}}\,\,\left( {\frac{{1\,\,{\text{h}}}}{{6\,\,{\text{miles}}}}\,\,\begin{array}{*{20}{c}}\\
\nearrow \\ \\
\nearrow \\
\end{array}} \right)\,\,\left( {\frac{{60\,\,{\text{minutes}}}}{{1\,\,h}}\,\,\begin{array}{*{20}{c}}\\
\nearrow \\ \\
\nearrow \\
\end{array}} \right)\,\,\, = \,\,20\,\,{\text{minutes}} \hfill \\ \\
\end{gathered} \right\}\,\,\,\, \Rightarrow \,\,\,\,?{\,_{{\text{temporary}}\,\,{\text{focus}}}}\,\, = \,\,\,32\,\,{\text{minutes}}\)
\({\text{? = }}\frac{{\text{4}}}{{32}} = \frac{1}{8}\)
Obs.: arrows indicate licit converters.
This solution follows the notations and rationale taught in the GMATH method.
Posts: 109
Can anyone tell me how do we solve this question if the distance is not given?
Posts: 137
Really the only trap here is to convert to MINUTE. Don't fall in to the trap of going with hour figures.
Avg speed = total distance/total time
total time = 12 mins + 20 mins
2 + 2 / 12 + 20 = 1/8
A
Avg speed = total distance/total time
total time = 12 mins + 20 mins
2 + 2 / 12 + 20 = 1/8
A
Why are the rates not additive here?
Automated notice from GMAT Club BumpBot:
A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.
This post was generated automatically.
_________________
A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.
This post was generated automatically.
_________________
Solving this question helps.
Taking a timed set of similar questions in
GMAT Club Forum Quiz →
is even better.
Moderator:
Announcements
Monday, Sep 14, 2026
11:30am NY / 3:30pm London / 9pm Mumbai
Subscribe to GMAT Club for New Podcast Episodes, Debriefs, & Insightful Sessions on GMAT Preparation
Tuck at Dartmouth
AI at Dartmouth Tuck: How the School Is Preparing Leaders for the Age of Artificial Intelligence
Inside the courses, research, and hands-on learning defining wise, decisive leadership in an AI-driven world.
Read More
Inside the courses, research, and hands-on learning defining wise, decisive leadership in an AI-driven world.
Read More
Top 5 GMAT Debrief Videos
Success stories and strategies from high-scoring candidates.