One-fifth of the light switches produced by a certain factory are defe : GMAT Problem Solving (PS)
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 18 Jan 2017, 04:21

### 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

# One-fifth of the light switches produced by a certain factory are defe

Author Message
TAGS:

### Hide Tags

Manager
Joined: 16 Apr 2009
Posts: 243
Schools: Ross
Followers: 3

Kudos [?]: 83 [1] , given: 10

One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

14 Aug 2009, 06:52
1
KUDOS
7
This post was
BOOKMARKED
00:00

Difficulty:

55% (hard)

Question Stats:

65% (02:57) correct 35% (02:18) wrong based on 301 sessions

### HideShow timer Statistics

One-fifth of the light switches produced by a certain factory are defective. Four-fifths of the defective switches are rejected and 1/20 of the non defective switches are rejected by mistake. If all the switches not rejected are sold, what percent of the switches sold by the factory are defective?

(A) 4%
(B) 5%
(C) 6.25%
(D) 11%
(E) 16%
[Reveal] Spoiler: OA

_________________

Keep trying no matter how hard it seems, it will get easier.

Last edited by Bunuel on 25 Apr 2015, 04:58, edited 2 times in total.
Renamed the topic, edited the question and added the OA.
Current Student
Joined: 18 Jun 2009
Posts: 358
Location: San Francisco
Followers: 10

Kudos [?]: 75 [0], given: 15

Re: One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

14 Aug 2009, 07:55
vannu wrote:
One-fifth of the light switches produced by a cer¬tain factory are defective. Four-fifths of the defective switches are rejected and of the nondefective switches are rejected by mistake. If all the switches not rejected are sold, what percent of the switches sold by the factory are defective?
(A) 4%
(B) 5%
(C) 6.25%
(D) 11%
(E) 16%
[Reveal] Spoiler:
B

I guess there is somethings missing here "Four-fifths of the defective switches are rejected and of the nondefective switches are rejected by mistake"
Manager
Joined: 25 Jul 2009
Posts: 116
Schools: NYU, NUS, ISB, DUKE, ROSS, DARDEN
Followers: 5

Kudos [?]: 229 [0], given: 17

Re: One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

14 Aug 2009, 07:59
vannu wrote:
One-fifth of the light switches produced by a cer¬tain factory are defective. Four-fifths of the defective switches are rejected and of the nondefective switches are rejected by mistake. If all the switches not rejected are sold, what percent of the switches sold by the factory are defective?
(A) 4%
(B) 5%
(C) 6.25%
(D) 11%
(E) 16%
[Reveal] Spoiler:
B

There seems to be some missing data in the highlighted part.
_________________

KUDOS me if I deserve it !!

My GMAT Debrief - 740 (Q50, V39) | My Test-Taking Strategies for GMAT | Sameer's SC Notes

Intern
Joined: 14 Aug 2009
Posts: 1
Followers: 0

Kudos [?]: 1 [0], given: 4

Re: One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

14 Aug 2009, 08:46
i too got confused by the highlighted sentence.. is the prblm statemnt clear..
Manager
Joined: 16 Apr 2009
Posts: 243
Schools: Ross
Followers: 3

Kudos [?]: 83 [0], given: 10

Re: One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

14 Aug 2009, 08:47
I edited the question. Sorry for the inconvenience.
_________________

Keep trying no matter how hard it seems, it will get easier.

SVP
Joined: 05 Jul 2006
Posts: 1743
Followers: 6

Kudos [?]: 316 [1] , given: 49

Re: One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

14 Aug 2009, 08:58
1
KUDOS
1
This post was
BOOKMARKED
vannu wrote:
One-fifth of the light switches produced by a cer¬tain factory are defective. Four-fifths of the defective switches are rejected and 1/20 th of the nondefective switches are rejected by mistake. If all the switches not rejected are sold, what percent of the switches sold by the factory are defective?
(A) 4%
(B) 5%
(C) 6.25%
(D) 11%
(E) 16%
[Reveal] Spoiler:
B

assume 1000 produced

200 defective , 160 defective and rejected, 40 nondefective rejected by mistake

40 defective and not rejected , 760 non defective and not rejected, total non rejected and sold = 800

percent of the switches sold by the factory are defective = 40/800*100 = 5%
Manager
Joined: 25 Jul 2009
Posts: 116
Schools: NYU, NUS, ISB, DUKE, ROSS, DARDEN
Followers: 5

Kudos [?]: 229 [3] , given: 17

Re: One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

14 Aug 2009, 09:03
3
KUDOS
1
This post was
BOOKMARKED
vannu wrote:
One-fifth of the light switches produced by a cer¬tain factory are defective. Four-fifths of the defective switches are rejected and 1/20 th of the nondefective switches are rejected by mistake. If all the switches not rejected are sold, what percent of the switches sold by the factory are defective?
(A) 4%
(B) 5%
(C) 6.25%
(D) 11%
(E) 16%
[Reveal] Spoiler:
B

Assume x as the number of switches and that x =100
Defective Switches = 1/5 * 100 = 20
Defective Switches that are rejected = 4/5 * 20 = 16
Defective Switches that are sold = 20 - 16 = 4

Non-defective Switches = 100 - 20 = 80
Non-defective Switches mistakenly rejected = 80*1/20 = 4
Non-defective Switches that are sold = 80 - 4 = 76

Total sold in the market = 76 + 4 = 80
% of defective = (4/80)*100 = 5%

ANS: B
_________________

KUDOS me if I deserve it !!

My GMAT Debrief - 740 (Q50, V39) | My Test-Taking Strategies for GMAT | Sameer's SC Notes

Senior Manager
Joined: 15 Feb 2011
Posts: 263
Followers: 4

Kudos [?]: 151 [0], given: 9

Re: One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

10 Jul 2011, 10:40
This may be a very stupid question but please help me understand how did we derive at(4/80)*100 ??

Is there a formula for this??
Math Forum Moderator
Joined: 20 Dec 2010
Posts: 2021
Followers: 161

Kudos [?]: 1703 [2] , given: 376

Re: One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

10 Jul 2011, 11:04
2
KUDOS
1
This post was
BOOKMARKED
vannu wrote:
One-fifth of the light switches produced by a certain factory are defective. Four-fifths of the defective switches are rejected and 1/20 th of the nondefective switches are rejected by mistake. If all the switches not rejected are sold, what percent of the switches sold by the factory are defective?
(A) 4%
(B) 5%
(C) 6.25%
(D) 11%
(E) 16%
[Reveal] Spoiler:
B

 Rejected Not Rejected Defective a b c Not Defective d e f g h i

Fill in this order:
i=100
1/5 of total= Defective i.e. 1/5*100=20 Defective. c=20
Not Defective=100-20=80, f=80

4/5 of Defective=Rejected= 4/5*20=16. a=16
b=c-a i.e. b=20-16=4

1/20 th of the nondefective switches are rejected
1/20*80=4. d=4
g=a+d=16+4=20

h=i-g=100-20=80

Defective+Not Rejected=b=4
Total Not Rejected=h=80

%=4/80*100=5

 Rejected Not Rejected Defective 16 4 20 Not Defective 4 e 80 20 80 100

Ans: "B"
_________________
Senior Manager
Joined: 15 Feb 2011
Posts: 263
Followers: 4

Kudos [?]: 151 [0], given: 9

Re: One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

10 Jul 2011, 11:15
thanks fluke, dis approach did help me understand the question better...

this was my first post..i have couple of more questions wherein i need your advice..pls suggest if i need to open up a new topic for every question or can i post my queries alongside the existing post..like what i did in this one..

thanks again!!
Math Forum Moderator
Joined: 20 Dec 2010
Posts: 2021
Followers: 161

Kudos [?]: 1703 [0], given: 376

Re: One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

10 Jul 2011, 11:51
DeeptiM wrote:
thanks fluke, dis approach did help me understand the question better...

this was my first post..i have couple of more questions wherein i need your advice..pls suggest if i need to open up a new topic for every question or can i post my queries alongside the existing post..like what i did in this one..

thanks again!!

Please reply to the existing post. If the question is not discussed before, create a new thread.
_________________
Current Student
Status: GMAT Date: 10/08/15
Joined: 17 Jul 2014
Posts: 97
Location: United States (MA)
Concentration: Human Resources, Strategy
GMAT 1: 640 Q48 V35
GPA: 3.5
WE: Human Resources (Consumer Products)
Followers: 0

Kudos [?]: 26 [0], given: 62

Re: One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

25 Apr 2015, 04:49
Option B --> 5 %

Just took 100 as the total number of switches and filled in numbers from there on.

Defective - 20 Non- Defective - 80
Rejected - 16 Rejected by mistake (1/20) - 4
Not rejected - 4 Net non-defective -- 80-4 = 76

# Sold but defective - 4
# sold - 76

--> 4/76 = ~5%

Thanks,
aimtoteach

Please give kudos if this helped!!

vannu wrote:
One-fifth of the light switches produced by a cer¬tain factory are defective. Four-fifths of the defective switches are rejected and 1/20 th of the nondefective switches are rejected by mistake. If all the switches not rejected are sold, what percent of the switches sold by the factory are defective?
(A) 4%
(B) 5%
(C) 6.25%
(D) 11%
(E) 16%
[Reveal] Spoiler:
B

_________________

Thanks,
aimtoteach

~~~~~~~~~~~~~~~~~

Please give Kudos if you find this post useful.

Math Expert
Joined: 02 Sep 2009
Posts: 36540
Followers: 7074

Kudos [?]: 93070 [0], given: 10541

Re: One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

25 Apr 2015, 04:59
vannu wrote:
One-fifth of the light switches produced by a certain factory are defective. Four-fifths of the defective switches are rejected and 1/20 of the non defective switches are rejected by mistake. If all the switches not rejected are sold, what percent of the switches sold by the factory are defective?

(A) 4%
(B) 5%
(C) 6.25%
(D) 11%
(E) 16%

Similar question to practice: one-fifth-of-the-batteries-produced-by-an-upstart-factory-are-defectiv-189100.html
_________________
Current Student
Status: GMAT Date: 10/08/15
Joined: 17 Jul 2014
Posts: 97
Location: United States (MA)
Concentration: Human Resources, Strategy
GMAT 1: 640 Q48 V35
GPA: 3.5
WE: Human Resources (Consumer Products)
Followers: 0

Kudos [?]: 26 [0], given: 62

Re: One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

25 Apr 2015, 05:08
Bunuel wrote:
vannu wrote:
One-fifth of the light switches produced by a certain factory are defective. Four-fifths of the defective switches are rejected and 1/20 of the non defective switches are rejected by mistake. If all the switches not rejected are sold, what percent of the switches sold by the factory are defective?

(A) 4%
(B) 5%
(C) 6.25%
(D) 11%
(E) 16%

Similar question to practice: one-fifth-of-the-batteries-produced-by-an-upstart-factory-are-defectiv-189100.html

Thank you Bunuel - it was a good one indeed!!

Thanks,
aimtoteach
_________________

Thanks,
aimtoteach

~~~~~~~~~~~~~~~~~

Please give Kudos if you find this post useful.

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 13435
Followers: 575

Kudos [?]: 163 [0], given: 0

Re: One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

07 Jun 2016, 00:50
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.
_________________
Intern
Joined: 21 Apr 2016
Posts: 30
Location: United States
Followers: 0

Kudos [?]: 1 [0], given: 11

Re: One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

01 Sep 2016, 07:35
fluke wrote:
vannu wrote:
One-fifth of the light switches produced by a certain factory are defective. Four-fifths of the defective switches are rejected and 1/20 th of the nondefective switches are rejected by mistake. If all the switches not rejected are sold, what percent of the switches sold by the factory are defective?
(A) 4%
(B) 5%
(C) 6.25%
(D) 11%
(E) 16%
[Reveal] Spoiler:
B

 Rejected Not Rejected Defective a b c Not Defective d e f g h i

Fill in this order:
i=100
1/5 of total= Defective i.e. 1/5*100=20 Defective. c=20
Not Defective=100-20=80, f=80

4/5 of Defective=Rejected= 4/5*20=16. a=16
b=c-a i.e. b=20-16=4

1/20 th of the nondefective switches are rejected
1/20*80=4. d=4
g=a+d=16+4=20

h=i-g=100-20=80

Defective+Not Rejected=b=4
Total Not Rejected=h=80

%=4/80*100=5

 Rejected Not Rejected Defective 16 4 20 Not Defective 4 e 80 20 80 100

Ans: "B"

Hello!
Somehow, I am completely missing the caveat for this problem!

I am getting an answer of 25% which is clearly wrong!
What am I doing wrong? I have attached the chart I am working off of attached here.
Is it something to do with the 'mistakenly labeled rejected' bit?

So confused!
Attachments

Screen Shot 2016-09-01 at 11.33.23 AM.png [ 29.23 KiB | Viewed 1442 times ]

Senior Manager
Joined: 07 Dec 2014
Posts: 490
Followers: 3

Kudos [?]: 81 [1] , given: 2

One-fifth of the light switches produced by a certain factory are defe [#permalink]

### Show Tags

01 Sep 2016, 13:48
1
KUDOS
One-fifth of the light switches produced by a certain factory are defective. Four-fifths of the defective switches are rejected and 1/20 of the non defective switches are rejected by mistake. If all the switches not rejected are sold, what percent of the switches sold by the factory are defective?

This made it easier for me.
.04/.8=.05=5%
Attachments

switches.png [ 24.47 KiB | Viewed 1268 times ]

One-fifth of the light switches produced by a certain factory are defe   [#permalink] 01 Sep 2016, 13:48
Similar topics Replies Last post
Similar
Topics:
3 In a certain factory, the production line which produces the bags has 5 05 Jan 2017, 04:51
2 A certain factory produces buttons and buckles at a uniform weight. If 1 05 Jul 2016, 11:18
9 One-fifth of the batteries produced by an upstart factory are defectiv 6 26 Nov 2014, 06:56
18 At a certain factory, 10 percent of the staplers produced on 6 25 Nov 2013, 11:49
15 In 2008, a certain factory produced 30% more widgets 7 24 Nov 2012, 07:28
Display posts from previous: Sort by