It is currently 14 Dec 2017, 07:25

Decision(s) Day!:

CHAT Rooms | Wharton R1 | Stanford R1 | Tuck R1 | Ross R1 | Haas R1


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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Three neighborhood children, individually, can mow Mr. Phelps's lawn i

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

Hide Tags

Manager
Manager
avatar
Joined: 13 Sep 2016
Posts: 101

Kudos [?]: 92 [0], given: 320

Three neighborhood children, individually, can mow Mr. Phelps's lawn i [#permalink]

Show Tags

New post 16 Oct 2016, 01:38
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

88% (01:13) correct 13% (00:54) wrong based on 64 sessions

HideShow timer Statistics

Three neighborhood children, individually, can mow Mr. Phelps's lawn in 1.5, 2, and 3 hours, respectively. What is the fastest the job can be completed by two of the children working together at their respective rates?

a) 6/7 hours
b) 3/2 hours
c) 7/4 hours
d) 7/2 hours
e) 5 hours

Please assist with above problem.
[Reveal] Spoiler: OA

Kudos [?]: 92 [0], given: 320

Expert Post
1 KUDOS received
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 42605

Kudos [?]: 135629 [1], given: 12705

Re: Three neighborhood children, individually, can mow Mr. Phelps's lawn i [#permalink]

Show Tags

New post 16 Oct 2016, 01:45
1
This post received
KUDOS
Expert's post
2
This post was
BOOKMARKED
alanforde800Maximus wrote:
Three neighborhood children, individually, can mow Mr. Phelps's lawn in 1.5, 2, and 3 hours, respectively. What is the fastest the job can be completed by two of the children working together at their respective rates?

a) 6/7 hours
b) 3/2 hours
c) 7/4 hours
d) 7/2 hours
e) 5 hours

Please assist with above problem.


The fastest children are those who can mow the lawn in 1.5 (3/2) and 2 hours. Their individual rates are 2/3 and 1/2 lawn/hour.

Their combined rate is 2/3 + 1/2 = 7/6 lawn/hour. The time is a reciprocal of the rate, thus working together at their respective rates these two children can mow the lawn in 6/7 hours.

Answer: A.
_________________

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

Kudos [?]: 135629 [1], given: 12705

1 KUDOS received
Board of Directors
User avatar
G
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 3111

Kudos [?]: 1148 [1], given: 327

Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
GMAT ToolKit User Premium Member
Re: Three neighborhood children, individually, can mow Mr. Phelps's lawn i [#permalink]

Show Tags

New post 16 Oct 2016, 02:34
1
This post received
KUDOS
alanforde800Maximus wrote:
Three neighborhood children, individually, can mow Mr. Phelps's lawn in 1.5, 2, and 3 hours, respectively. What is the fastest the job can be completed by two of the children working together at their respective rates?

a) 6/7 hours
b) 3/2 hours
c) 7/4 hours
d) 7/2 hours
e) 5 hours

Please assist with above problem.


Let the total work be 6 units...

Efficiency of child A = 6/1.5 = 4 units/hour
Efficiency of child B = 6/2 = 3 units/hour
Efficiency of child C = 6/3 = 2 units/hour

Quote:
What is the fastest the job can be completed by two of the children working together at their respective rates?


Since the efficiency of child A and Child B are faster than C , their combined efficiency is 7 ( ie, 4 + 3 )

So, Time taken by A and B working at their respective rates is 6/7

Hence correct answer must be (A)

_________________

Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )

Kudos [?]: 1148 [1], given: 327

Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 14840

Kudos [?]: 287 [0], given: 0

Premium Member
Re: Three neighborhood children, individually, can mow Mr. Phelps's lawn i [#permalink]

Show Tags

New post 21 Nov 2017, 12:38
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

Kudos [?]: 287 [0], given: 0

Re: Three neighborhood children, individually, can mow Mr. Phelps's lawn i   [#permalink] 21 Nov 2017, 12:38
Display posts from previous: Sort by

Three neighborhood children, individually, can mow Mr. Phelps's lawn i

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


GMAT Club MBA Forum Home| About| Terms and Conditions| 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®.