It is currently 19 Oct 2017, 08:06

STARTING SOON:

Live Chat with Cornell Adcoms in Main Chat Room  |  R1 Interview Invites: MIT Sloan Chat  |  UCLA Anderson Chat  |  Duke Fuqua Chat (EA Decisions)


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

In a shipment of 120 machine parts, 5 percent were defective

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

Hide Tags

Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 41893

Kudos [?]: 128862 [0], given: 12183

In a shipment of 120 machine parts, 5 percent were defective [#permalink]

Show Tags

New post 13 Feb 2014, 02:29
Expert's post
2
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

88% (00:42) correct 12% (00:42) wrong based on 576 sessions

HideShow timer Statistics

The Official Guide For GMAT® Quantitative Review, 2ND Edition

In a shipment of 120 machine parts, 5 percent were defective. In a shipment of 80 machine parts, 10 percent were defective. For the two shipments combined, what percent of the machine parts were defective?

(A) 6.5%
(B) 7.0%
(C) 7.5%
(D) 8.0%
(E) 8.5%

Problem Solving
Question: 95
Category: Arithmetic Percents
Page: 74
Difficulty: 550


GMAT Club is introducing a new project: The Official Guide For GMAT® Quantitative Review, 2ND Edition - Quantitative Questions Project

Each week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution.

We'll be glad if you participate in development of this project:
1. Please provide your solutions to the questions;
2. Please vote for the best solutions by pressing Kudos button;
3. Please vote for the questions themselves by pressing Kudos button;
4. Please share your views on difficulty level of the questions, so that we have most precise evaluation.

Thank you!
[Reveal] Spoiler: OA

_________________

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 [?]: 128862 [0], given: 12183

Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 41893

Kudos [?]: 128862 [0], given: 12183

In a shipment of 120 machine parts, 5 percent were defective [#permalink]

Show Tags

New post 13 Feb 2014, 02:30
Expert's post
1
This post was
BOOKMARKED
SOLUTION

In a shipment of 120 machine parts, 5 percent were defective. In a shipment of 80 machine parts, 10 percent were defective. For the two shipments combined, what percent of the machine parts were defective?

(A) 6.5%
(B) 7.0%
(C) 7.5%
(D) 8.0%
(E) 8.5%

For the two shipments combined, the percent of defective parts = (total # of defective parts)/(total # of parts)*100 = \(\frac{120*0.05+80*0.1}{120+80}*100=7%\).

Answer: B.
_________________

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 [?]: 128862 [0], given: 12183

Current Student
User avatar
Joined: 25 Sep 2012
Posts: 287

Kudos [?]: 174 [0], given: 242

Location: India
Concentration: Strategy, Marketing
GMAT 1: 660 Q49 V31
GMAT 2: 680 Q48 V34
GMAT ToolKit User Reviews Badge
Re: In a shipment of 120 machine parts, 5 percent were defective [#permalink]

Show Tags

New post 13 Feb 2014, 02:53
5% of 120 is 6
10% of 80 is 8

As the question says two shipments combined, we have two add the defective as well as total shipments.

8+6/120+80 = 15/200 = 7.5%
Answer C

There are many different ways to calculate percentages, I think the best way here can be like this
To find 10% of any no. just move one decimal point to left (10% of 120 = 12) and (10% of 80 = 8)
To find 5% of any no. just halve the above no. (5% of 120 = 12/2 = 6)

Kudos [?]: 174 [0], given: 242

1 KUDOS received
Intern
Intern
avatar
Joined: 15 Nov 2013
Posts: 3

Kudos [?]: 1 [1], given: 28

Re: In a shipment of 120 machine parts, 5 percent were defective [#permalink]

Show Tags

New post 13 Feb 2014, 04:23
1
This post received
KUDOS
b2bt

Good logic, but I think you made a little error in your calculations.

(8+6)/(120+80) = 14/200, which leads to 7%

Answer is B.

Kudos [?]: 1 [1], given: 28

1 KUDOS received
Manager
Manager
avatar
Joined: 04 Oct 2013
Posts: 162

Kudos [?]: 119 [1], given: 55

Location: India
GMAT Date: 05-23-2015
GPA: 3.45
GMAT ToolKit User Premium Member Reviews Badge
Re: In a shipment of 120 machine parts, 5 percent were defective [#permalink]

Show Tags

New post 13 Feb 2014, 22:12
1
This post received
KUDOS
In a shipment of 120 machine parts, 5 percent were defective. In a shipment of 80 machine parts, 10 percent were defective. For the two shipments combined, what percent of the machine parts were defective?

(A) 6.5%
(B) 7.0%
(C) 7.5%
(D) 8.0%
(E) 8.5%



\(TotalDefectiveMachineParts = (\frac{5}{100})120 + (\frac{10}{100})80 = 6 + 8 =14\)

So, \(%\) \(OfDefectiveMachineParts= = \frac{Total Defective Machine Parts}{Total Machine Parts}=\frac{14}{200} = \frac{7}{100}=7%\)

Answer: (B)

Kudos [?]: 119 [1], given: 55

1 KUDOS received
Manager
Manager
User avatar
Status: GMATting
Joined: 21 Mar 2011
Posts: 108

Kudos [?]: 105 [1], given: 104

Concentration: Strategy, Technology
GMAT 1: 590 Q45 V27
GMAT ToolKit User
Re: In a shipment of 120 machine parts, 5 percent were defective [#permalink]

Show Tags

New post 14 Feb 2014, 02:34
1
This post received
KUDOS
Defective 1= 5% of 120 = 6;
Defective 2= 10% of 80 = 8;

Total Defective = 6 + 8 = 14/(120 + 80) = 14/200 = 7/100 = 7%;

Ans is (B).

Kudos [?]: 105 [1], given: 104

Current Student
User avatar
Joined: 25 Sep 2012
Posts: 287

Kudos [?]: 174 [0], given: 242

Location: India
Concentration: Strategy, Marketing
GMAT 1: 660 Q49 V31
GMAT 2: 680 Q48 V34
GMAT ToolKit User Reviews Badge
Re: In a shipment of 120 machine parts, 5 percent were defective [#permalink]

Show Tags

New post 15 Feb 2014, 05:04
bradburyj wrote:
b2bt

Good logic, but I think you made a little error in your calculations.

(8+6)/(120+80) = 14/200, which leads to 7%

Answer is B.


Oops :(
I always tend to make calculation mistakes.

Kudos [?]: 174 [0], given: 242

1 KUDOS received
Current Student
User avatar
Joined: 03 Feb 2013
Posts: 942

Kudos [?]: 1057 [1], given: 548

Location: India
Concentration: Operations, Strategy
GMAT 1: 760 Q49 V44
GPA: 3.88
WE: Engineering (Computer Software)
Reviews Badge
Re: In a shipment of 120 machine parts, 5 percent were defective [#permalink]

Show Tags

New post 15 Feb 2014, 10:44
1
This post received
KUDOS
Bunuel wrote:
The Official Guide For GMAT® Quantitative Review, 2ND Edition

In a shipment of 120 machine parts, 5 percent were defective. In a shipment of 80 machine parts, 10 percent were defective. For the two shipments combined, what percent of the machine parts were defective?

(A) 6.5%
(B) 7.0%
(C) 7.5%
(D) 8.0%
(E) 8.5%



Out of 120 , 5% are defective.
Lets try to calculate without putting pen (read marker) to paper (read scratch pad).
10% of 120 is 12 (remove the last 0 from numerator).
Half of 12 = 6 should be 5%

and Out of 80, 10% is defective. so 8
so 8+6 = 14 out of 200 (120+80) so 14/2 should be the required answer = 7% - Option B)
_________________

Thanks,
Kinjal
My Debrief : http://gmatclub.com/forum/hardwork-never-gets-unrewarded-for-ever-189267.html#p1449379
My Application Experience : http://gmatclub.com/forum/hardwork-never-gets-unrewarded-for-ever-189267-40.html#p1516961
Linkedin : https://www.linkedin.com/in/kinjal-das/

Please click on Kudos, if you think the post is helpful

Kudos [?]: 1057 [1], given: 548

1 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 20 Dec 2013
Posts: 267

Kudos [?]: 106 [1], given: 29

Location: India
Re: In a shipment of 120 machine parts, 5 percent were defective [#permalink]

Show Tags

New post 16 Feb 2014, 02:56
1
This post received
KUDOS
Option B
Def in ship. 1: 120 *5%=6 +
Def. in ship. 2:80 * 10%=8
Total def=14
Total no.=120+80=200
%age def in total=14 *100/200=7%

Kudos [?]: 106 [1], given: 29

1 KUDOS received
Manager
Manager
User avatar
Status: Never Give up!!!
Joined: 03 Aug 2012
Posts: 51

Kudos [?]: 43 [1], given: 28

Location: India
Concentration: Finance, General Management
GMAT ToolKit User
Re: In a shipment of 120 machine parts, 5 percent were defective [#permalink]

Show Tags

New post 16 Feb 2014, 06:07
1
This post received
KUDOS
Option B - 7%
5% of 120 - 6 pieces
10% of 80 - 8 pieces

If both are combined - total pieces - 200
Total defective pieces - 14
So % defective pieces - 14/200 = 7%

Kudos [?]: 43 [1], given: 28

Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 41893

Kudos [?]: 128862 [0], given: 12183

Re: In a shipment of 120 machine parts, 5 percent were defective [#permalink]

Show Tags

New post 17 Feb 2014, 01:21
SOLUTION

In a shipment of 120 machine parts, 5 percent were defective. In a shipment of 80 machine parts, 10 percent were defective. For the two shipments combined, what percent of the machine parts were defective?

(A) 6.5%
(B) 7.0%
(C) 7.5%
(D) 8.0%
(E) 8.5%

For the two shipments combined, the percent of defective parts = (total # of defective parts)/(total # of parts)*100 = \(\frac{120*0.05+80*0.1}{120+80}*100=7%\).

Answer: C.
_________________

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 [?]: 128862 [0], given: 12183

Manager
Manager
avatar
Status: suffer now and live forever as a champion!!!
Joined: 01 Sep 2013
Posts: 147

Kudos [?]: 71 [0], given: 75

Location: India
Dheeraj: Madaraboina
GPA: 3.5
WE: Information Technology (Computer Software)
Premium Member
Re: In a shipment of 120 machine parts, 5 percent were defective [#permalink]

Show Tags

New post 23 Apr 2014, 23:43
for 120 shipments , 5% i.e 6 were defective .
for 80 shipments, 10% i.e 8 were defective.

Total = 200 shipments (combined) and defective =14 (combined).
question asks us 14 is what % of 200.

14/200 = x/100;
x=7% ;

Press kudos if this helps :)

Kudos [?]: 71 [0], given: 75

Intern
Intern
avatar
B
Joined: 26 Jul 2014
Posts: 12

Kudos [?]: 1 [0], given: 10

GMAT ToolKit User
Re: In a shipment of 120 machine parts, 5 percent were defective [#permalink]

Show Tags

New post 05 Aug 2017, 07:57
Another solution:
Call x (%) is percent of the machine parts were defective for the two shipments combined.
120/80=(10-x)/(x-5)
=> 120 (x-5) = 80(10-x)
=> 20x = 140
=> x = 7 (%)

Kudos [?]: 1 [0], given: 10

Manager
Manager
User avatar
B
Joined: 21 Jun 2017
Posts: 70

Kudos [?]: 4 [0], given: 2

Re: In a shipment of 120 machine parts, 5 percent were defective [#permalink]

Show Tags

New post 22 Aug 2017, 13:38
1. 120 x 5 = 600 = move decimal two digits left because percent = 6 parts defective from 120 shipment
2. 80 x 10 = 800 = 8 (move decimal again) parts defective
3. Find total parts = 120 + 80 = 200
4. Find total defective parts = 6 + 8 = 14
5. (14 / 200) x 100 = 7% parts defective

Answer is (B) 7.0%

Kudos [?]: 4 [0], given: 2

Expert Post
Target Test Prep Representative
User avatar
S
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 1634

Kudos [?]: 838 [0], given: 2

Location: United States (CA)
Re: In a shipment of 120 machine parts, 5 percent were defective [#permalink]

Show Tags

New post 24 Aug 2017, 16:35
Bunuel wrote:
The Official Guide For GMAT® Quantitative Review, 2ND Edition

In a shipment of 120 machine parts, 5 percent were defective. In a shipment of 80 machine parts, 10 percent were defective. For the two shipments combined, what percent of the machine parts were defective?

(A) 6.5%
(B) 7.0%
(C) 7.5%
(D) 8.0%
(E) 8.5%


In the shipment of 120 machine parts, 120 x 0.05 = 6 were defective. In the shipment of 80 machine parts, 80 x 0.1 = 8 were defective. Thus, 14/200 = 7/100 = 7% were defective overall.

Answer: B
_________________

Scott Woodbury-Stewart
Founder and CEO

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

Kudos [?]: 838 [0], given: 2

Re: In a shipment of 120 machine parts, 5 percent were defective   [#permalink] 24 Aug 2017, 16:35
Display posts from previous: Sort by

In a shipment of 120 machine parts, 5 percent were defective

  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®.