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

 It is currently 19 Feb 2019, 19:17

### 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

## Events & Promotions

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

February 20, 2019

February 20, 2019

08:00 PM EST

09:00 PM EST

Strategies and techniques for approaching featured GMAT topics. Wednesday, February 20th at 8 PM EST
• ### Online GMAT boot camp for FREE

February 21, 2019

February 21, 2019

10:00 PM PST

11:00 PM PST

Kick off your 2019 GMAT prep with a free 7-day boot camp that includes free online lessons, webinars, and a full GMAT course access. Limited for the first 99 registrants! Feb. 21st until the 27th.

# Jenny drove to the gym with an average speed of 60 miles per hour. On

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

### Hide Tags

Intern
Joined: 26 Apr 2018
Posts: 39
Jenny drove to the gym with an average speed of 60 miles per hour. On  [#permalink]

### Show Tags

01 Oct 2018, 07:20
2
00:00

Difficulty:

25% (medium)

Question Stats:

79% (01:48) correct 21% (01:39) wrong based on 97 sessions

### HideShow timer Statistics

Jenny drove to the gym with an average speed of 60 miles per hour. On her way back she drove the same route with an average speed of 80 miles per hour. What was er average speed for the whole trip in mph?

a) 60

b) 68

c) 68 4/7

d) 70

e) 74 3/8

source gmat tutor
Math Expert
Joined: 02 Aug 2009
Posts: 7334
Re: Jenny drove to the gym with an average speed of 60 miles per hour. On  [#permalink]

### Show Tags

01 Oct 2018, 07:35
bettatantalo wrote:
Jenny drove to the gym with an average speed of 60 miles per hour. On her way back she drove the same route with an average speed of 80 miles per hour. What was er average speed for the whole trip in mph?

a) 60

b) 68

c) 68 4/7

d) 70

e) 74 3/8

source gmat tutor

Direct formula...
$$\frac{2*a*b}{a+b}=\frac{2*60*80}{60+80}$$=960/14=480/7=68 4/7

C

Otherwise..
Let the distance be d..
d/60 +d/80 =3d+4d/240.. = total time taken
Average speed = 2d/(7d/240)=480/7

C
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html
4) Base while finding % increase and % decrease : https://gmatclub.com/forum/percentage-increase-decrease-what-should-be-the-denominator-287528.html

GMAT Expert

CEO
Joined: 11 Sep 2015
Posts: 3435
Location: Canada
Re: Jenny drove to the gym with an average speed of 60 miles per hour. On  [#permalink]

### Show Tags

01 Oct 2018, 09:23
Top Contributor
bettatantalo wrote:
Jenny drove to the gym with an average speed of 60 miles per hour. On her way back she drove the same route with an average speed of 80 miles per hour. What was er average speed for the whole trip in mph?

a) 60

b) 68

c) 68 4/7

d) 70

e) 74 3/8

Another approach is to assign a "nice" value (one that works well with 60 mph and 80 mph) to the distance to the gym.
So, let's say the distance is 480 miles (a long commute indeed!)

Average speed = (total distance traveled)/(total travel time)

TOTAL distance = 480 miles + 480 miles = 960 miles

Now let's calculate the TOTAL travel time.

time = distance/speed
So, travel time TO the gym = 480/60 = 8 hours
And travel time FROM the gym = 480/80 = 6 hours
So, TOTAL travel time = 8 hours + 6 hours = 14 hours

So, average speed = 960 miles/14 hours
= 480/7 miles per hour
= 68 4/7 miles per hour

Answer: C

RELATED VIDEO FROM OUR COURSE

_________________

Test confidently with gmatprepnow.com

Manager
Joined: 05 Oct 2017
Posts: 65
GMAT 1: 560 Q44 V23
Re: Jenny drove to the gym with an average speed of 60 miles per hour. On  [#permalink]

### Show Tags

02 Oct 2018, 00:41
1
bettatantalo wrote:
Jenny drove to the gym with an average speed of 60 miles per hour. On her way back she drove the same route with an average speed of 80 miles per hour. What was er average speed for the whole trip in mph?

a) 60

b) 68

c) 68 4/7

d) 70

e) 74 3/8

source gmat tutor

If the distance from home to gym is D, then total distance =2D
time from Home to Gym T1=D/60
time from Gym to home T2=D/80

average speed = total distance/(T1+T2)
= 2D/(D/60+D80)
=68 4/7
answer is C
_________________

It’s not that I’m so smart, it’s just that I stay with problems longer. -- Albert Einstein

Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 4940
Location: United States (CA)
Re: Jenny drove to the gym with an average speed of 60 miles per hour. On  [#permalink]

### Show Tags

03 Oct 2018, 16:42
bettatantalo wrote:
Jenny drove to the gym with an average speed of 60 miles per hour. On her way back she drove the same route with an average speed of 80 miles per hour. What was er average speed for the whole trip in mph?

a) 60

b) 68

c) 68 4/7

d) 70

e) 74 3/8

We can let the distance each way = 240 miles and use the formula: average rate = total distance/total time:

average rate = 480/(4 + 3) = 480/7 = 68 4/7

Answer: C
_________________

Scott Woodbury-Stewart
Founder and CEO

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

Re: Jenny drove to the gym with an average speed of 60 miles per hour. On   [#permalink] 03 Oct 2018, 16:42
Display posts from previous: Sort by

# Jenny drove to the gym with an average speed of 60 miles per hour. On

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 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®.