It is currently 23 Nov 2020, 10:44

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

GRE Math Challenge #7-David drove to work at an average

Author Message
TAGS:
Director
Joined: 16 May 2014
Posts: 597
GRE 1: Q165 V161
Followers: 116

Kudos [?]: 683 [1] , given: 64

GRE Math Challenge #7-David drove to work at an average [#permalink]  15 Sep 2014, 22:03
1
KUDOS
Expert's post
00:00

Question Stats:

58% (01:15) correct 41% (01:21) wrong based on 131 sessions
David drove to work at an average (arithmetic mean) speed of 45 miles per hour. After work, David drove home at an average speed of 60 miles per hour. If David spent a total of 2 hours commuting to and from work, how many miles does David drive to work?

A)48
B)$$\frac{256}{5}$$
C)$$\frac{360}{7}$$
D)$$\frac{105}{2}$$
E)$$\frac{160}{3}$$
[Reveal] Spoiler: OA

_________________

My GRE Resources
Free GRE resources | GRE Prep Club Quant Tests
If you find this post helpful, please press the kudos button to let me know !

Intern
Joined: 26 Jan 2018
Posts: 5
Followers: 0

Kudos [?]: 0 [0], given: 4

Re: GRE Math Challenge #7-David drove to work at an average [#permalink]  27 Jan 2018, 21:36
D
Moderator
Joined: 07 Jan 2018
Posts: 697
Followers: 11

Kudos [?]: 785 [1] , given: 88

Re: GRE Math Challenge #7-David drove to work at an average [#permalink]  02 Feb 2018, 08:55
1
KUDOS
The total distance going from home to work = total distance going from work to home
In the 1st case David drove @ an average speed of 45 miles per hour so distance $$d = 45 h1$$where $$h1$$is the time taken to complete the distance
In the 2nd case David drove @ an average speed of 60 miles per hour so distance $$d = 60 h2$$where $$h2$$is the time taken to complete the return journey from work to home
Given,
$$h1 + h2 = 2$$
we get,$$h1 = 2 - h2$$
Since distance is equal for going to work from home and coming back to home from work
$$45h1 = 60h2$$
hence, $$45(2 - h2) = 60 h2$$
solve for h2 it should equal$$\frac{90}{105}$$
Solve for D by replacing value of h2 in the eqn $$60* h2$$
$$d =\frac{360}{7}$$
(C)
_________________

Need Practice? 20 Free GRE Quant Tests available for free with 20 Kudos

Intern
Joined: 07 Oct 2017
Posts: 30
Followers: 2

Kudos [?]: 6 [0], given: 0

Re: GRE Math Challenge #7-David drove to work at an average [#permalink]  03 Feb 2018, 04:10
Great Job!!!
Intern
Joined: 24 Dec 2017
Posts: 1
Followers: 0

Kudos [?]: 0 [0], given: 0

Re: GRE Math Challenge #7-David drove to work at an average [#permalink]  03 Feb 2018, 07:55
C : 360/7
Manager
Joined: 15 Feb 2018
Posts: 53
Followers: 1

Kudos [?]: 25 [0], given: 33

Re: GRE Math Challenge #7-David drove to work at an average [#permalink]  25 Feb 2018, 05:35
From home to work: 45 = t1*d
From work to home: 60 = t2*d

The distance d is the same for both trips, and also t1 + t2 = 2

So t1 = d/45 and t2 = d/60.

Substitute away t1 and t2 in the total time equation: d/45 + d/60 = 2.

Now solving for d: (60d + 45d)/2700 = 2 --> 105*d = 5,400 --> d = 360/7.
Manager
Joined: 26 Jan 2018
Posts: 189
GRE 1: Q165 V156
Followers: 1

Kudos [?]: 136 [0], given: 3

Re: GRE Math Challenge #7-David drove to work at an average [#permalink]  11 Apr 2018, 21:36
speed = distance/ time

We will get 2 equation for 1. To office and 2. Back from office.

Solving for 2 variables from 2 equations gives the answer.
Intern
Joined: 10 Jun 2018
Posts: 32
Followers: 0

Kudos [?]: 21 [0], given: 4

Re: GRE Math Challenge #7-David drove to work at an average [#permalink]  03 Sep 2018, 17:54
the equation is x/45 + x/60 = 2 ==> x = 360/7

where X is the distance between home and office.
Target Test Prep Representative
Joined: 12 Sep 2018
Posts: 208
Followers: 12

Kudos [?]: 134 [2] , given: 0

Re: GRE Math Challenge #7-David drove to work at an average [#permalink]  07 Mar 2019, 06:57
2
KUDOS
Expert's post
soumya1989 wrote:
David drove to work at an average (arithmetic mean) speed of 45 miles per hour. After work, David drove home at an average speed of 60 miles per hour. If David spent a total of 2 hours commuting to and from work, how many miles does David drive to work?

A)48
B)$$\frac{256}{5}$$
C)$$\frac{360}{7}$$
D)$$\frac{105}{2}$$
E)$$\frac{160}{3}$$

We can let d = the distance each way and create the equation for time:

d/45 + d/60 = 2

Multiplying by 180, we have:

4d + 3d = 360

7d = 360

d = 360/7

_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
41 Reviews

5-star rated online GRE quant
self study course

See why Target Test Prep is the top rated GRE quant course on GRE Prep Club. Read Our Reviews

GRE Instructor
Joined: 10 Apr 2015
Posts: 3903
Followers: 162

Kudos [?]: 4756 [0], given: 70

Re: GRE Math Challenge #7-David drove to work at an average [#permalink]  23 Apr 2020, 07:42
Expert's post
soumya1989 wrote:
David drove to work at an average (arithmetic mean) speed of 45 miles per hour. After work, David drove home at an average speed of 60 miles per hour. If David spent a total of 2 hours commuting to and from work, how many miles does David drive to work?

A)48
B)$$\frac{256}{5}$$
C)$$\frac{360}{7}$$
D)$$\frac{105}{2}$$
E)$$\frac{160}{3}$$

We can write: (David's travel time TO work) + (David's travel time FROM work) = 2 hours
time = distance/speed

Let d = the distance each way

We can write: d/45 + d/60 = 2
To eliminate the fractions, multiply both sides by 180, the LCM of 45 and 60

We get: 4d + 3d = 360
Simplify: 7d = 360
Solve: d = 360/7

Cheers,
Brent
_________________

Brent Hanneson – Creator of greenlighttestprep.com

Re: GRE Math Challenge #7-David drove to work at an average   [#permalink] 23 Apr 2020, 07:42
Display posts from previous: Sort by