Check GMAT Club Decision Tracker for the Latest School Decision Releases https://gmatclub.com/AppTrack

 It is currently 25 May 2017, 11:22

### 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 June
Open Detailed Calendar

# Four carpenters can individually complete a particular task

Author Message
TAGS:

### Hide Tags

Intern
Joined: 26 May 2012
Posts: 9
GMAT Date: 07-04-2012
Followers: 0

Kudos [?]: 5 [0], given: 8

### Show Tags

05 Jun 2012, 10:02
4
This post was
BOOKMARKED
00:00

Difficulty:

25% (medium)

Question Stats:

80% (02:47) correct 20% (02:39) wrong based on 282 sessions

### HideShow timer Statistics

Four carpenters can individually complete a particular task in 3, 4, 5, and 7 hours, respectively. What is the maximum fraction of the task that can be completed in forty-five minutes if three of the carpenters work together at their respective rates ?

A. 11/15
B. 3/5
C. 11/30
D. 47/80
E. 5/9
[Reveal] Spoiler: OA
Math Expert
Joined: 02 Sep 2009
Posts: 38870
Followers: 7731

Kudos [?]: 106113 [1] , given: 11607

### Show Tags

05 Jun 2012, 10:21
1
KUDOS
Expert's post
1
This post was
BOOKMARKED
Four carpenters can individually complete a particular task in 3, 4, 5, and 7 hours, respectively. What is the maximum fraction of the task that can be completed in forty-five minutes if three of the carpenters work together at their respective rates ?

A. 11/15
B. 3/5
C. 11/30
D. 47/80
E. 5/9

In order three of the carpenters to complete the maximum fraction of the task we should select three fastest carpenters. So, those three who complete the task in 3, 4, and 5 hours.

In 1 hour they will complete $$\frac{1}{3}+\frac{1}{4}+\frac{1}{5}=\frac{47}{60}$$th of the task. So, in $$\frac{3}{4}$$ hour (45 minutes) they will complete $$\frac{47}{60}*\frac{3}{4}=\frac{47}{80}$$th of the job.

Hope it's clear.
_________________
Current Student
Joined: 08 Jan 2009
Posts: 326
GMAT 1: 770 Q50 V46
Followers: 25

Kudos [?]: 146 [0], given: 7

### Show Tags

05 Jun 2012, 15:33
1/3 + 1/4 + 1/5 = 47/60
47/60 * 3/4 = 47 / 80

D
Manager
Status: Rising GMAT Star
Joined: 05 Jun 2012
Posts: 132
Location: Philippines
Concentration: General Management, Finance
GPA: 3.22
WE: Corporate Finance (Consulting)
Followers: 7

Kudos [?]: 56 [0], given: 16

### Show Tags

05 Jun 2012, 18:05
Four carpenters can individually complete a particular task in 3, 4, 5, and 7 hours, respectively. What is the maximum fraction of the task that can be completed in forty-five minutes if three of the carpenters work together at their respective rates ?

A. 11/15
B. 3/5
C. 11/30
D. 47/80
E. 5/9

Farmer A, B, C, and D

A's rate: 1/3 job/hour
B's rate: 1/4 job/hour
C's rate: 1/5 job/hour
D's rate: 1/7 job/hour

By intuition we know that the three fastest farmers are A B and C.

As such

(1/3 + 1/4 + 1/5)*(3/4) = ?

47/80 or (D)
_________________

Far better is it to dare mighty things, to win glorious triumphs, even though checkered by failure... than to rank with those poor spirits who neither enjoy nor suffer much, because they live in a gray twilight that knows not victory nor defeat.
- T. Roosevelt

Math Expert
Joined: 02 Sep 2009
Posts: 38870
Followers: 7731

Kudos [?]: 106113 [0], given: 11607

### Show Tags

14 Jun 2013, 05:27
Bumping for review and further discussion*. Get a kudos point for an alternative solution!

*New project from GMAT Club!!! Check HERE

All DS Min/Max Problems to practice: search.php?search_id=tag&tag_id=42
All PS Min/Max Problems to practice: search.php?search_id=tag&tag_id=63

_________________
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 15439
Followers: 649

Kudos [?]: 209 [0], given: 0

### Show Tags

07 Aug 2015, 11:50
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 Club Legend
Joined: 09 Sep 2013
Posts: 15439
Followers: 649

Kudos [?]: 209 [0], given: 0

### Show Tags

20 May 2017, 00:04
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.
_________________
Manager
Joined: 22 Aug 2013
Posts: 177
Location: India
Followers: 1

Kudos [?]: 29 [0], given: 217

### Show Tags

20 May 2017, 00:54
I sometimes do these by taking total work as number of units which is LCM of individual times.
LCM of 3,4,5,7 = 420.

Let total work be 420 units.
Carpenter A does in 1 hour = 420/3 = 140 units.
Carpenter B does in 1 hour = 420/4 = 105 units.
Carpenter C does in 1 hour = 420/5 = 84 units.
Carpenter D does in 1 hour = 420/7 = 60 units.

Clearly, 3 most efficient carpenters are A, B, C. So if we want to find out Max fraction of work possible by 3 carpenters, we have to take these 3 carpenters only.
They do a total of (140+105+84) = 329 units per hour

Now, 45 minutes = 3/4 hours
Work done in 1 hour = 329 units
Work done in 3/4 hours = 329 * 3/4 = 987/4

Now this is what fraction of total work = (987/4)/420 = 47/80.
Hence D

(This is a time taking solution for this question no doubt. Method given by others is better. But I am just trying to add some value by giving an alternate solution. This kind of method can be applied to such questions though, sometimes making them easier)
Re: Four carpenters can individually complete a particular task   [#permalink] 20 May 2017, 00:54
Similar topics Replies Last post
Similar
Topics:
2 Working alone, Bud can complete a particular task in 6 hours. Lou, wor 3 03 May 2017, 22:05
15 A and B can complete a task in 20 days. B and C can c 13 15 May 2017, 04:04
1 6 machines working at a constant rate can complete one task 2 05 Aug 2014, 11:06
3 If ‘A’ can complete a task in 3 hours and ‘B’ can complete 13 01 Mar 2016, 22:27
37 John can complete a given task in 20 days. Jane will take 16 30 May 2016, 03:59
Display posts from previous: Sort by