Find all School-related info fast with the new School-Specific MBA Forum

It is currently 29 Jun 2016, 10:24
GMAT Club Tests

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

One-fifth of the light switches produced by a certain

  post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Manager
Manager
avatar
Joined: 05 Sep 2007
Posts: 144
Location: New York
Followers: 1

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

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

Show Tags

New post 27 Mar 2008, 19:29
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

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%
Director
Director
avatar
Joined: 10 Sep 2007
Posts: 947
Followers: 8

Kudos [?]: 254 [0], given: 0

Re: PS: Light swt [#permalink]

Show Tags

New post 27 Mar 2008, 20:37
Assume total bulbs are 100.
Out of these 1/5th are defective = 100/5 = 20
In defective 4/5 are rejected = 20*4/5 = 16
So remaining bulbs are selected and sold = 20 - 16 = 4

Non-defective bulbs = 100 - 20 = 80
Wrongly rejected = 80/20 = 4
Remaining bulbs for selling = 80 - 4 = 76

So total bulbs available for selling = 4 (defective bulbs) + 76 (non-defective) = 80 Bulbs

Percentage = 4*100/80 = 5%

Answer B.
SVP
SVP
User avatar
Joined: 29 Aug 2007
Posts: 2492
Followers: 65

Kudos [?]: 669 [0], given: 19

Re: PS: Light swt [#permalink]

Show Tags

New post 27 Mar 2008, 20:38
el1981 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%


d= defective
nd= not defective
r = rejected
s = sold

d = 1/5
r(d) = (4/5) (1/5) = 4/25
r(nd) = 1/20 (4/5) = 1/25
Total r = 4/25 + 1/25 = 5/25 = 1/5
sold = 1 - 1/5 = 4/5
s(d) = 1/5 - 4/25 = 1/25

the percent of the defective switches sold by the factory = (1/25)/(4/5) = 1/20 = 5%. so B.

Assigning values also help solve the problem easily.
t = 100
d = 1/5 x 100 = 20
r(d) = 4/5 x 20 = 16
r(nd) = 1/20 x 80 = 4
r = 16+ 4 = 20
s = t - r = 100 - 20 = 80
s(d) = not r(d) = d - r(d) = 20 - 16 = 4
% of defective sold = 4/80 = 5%
_________________

Verbal: new-to-the-verbal-forum-please-read-this-first-77546.html
Math: new-to-the-math-forum-please-read-this-first-77764.html
Gmat: everything-you-need-to-prepare-for-the-gmat-revised-77983.html


GT

Re: PS: Light swt   [#permalink] 27 Mar 2008, 20:38
Display posts from previous: Sort by

One-fifth of the light switches produced by a certain

  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 and phpBB SEO

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®.