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

 It is currently 23 May 2015, 05:42

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

Author Message
TAGS:
Senior Manager
Joined: 13 Mar 2007
Posts: 295
Location: Russia, Moscow
Followers: 2

Kudos [?]: 22 [0], given: 0

One-fifth of the light switches produced by a certain [#permalink]  29 Mar 2007, 05:19
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 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%
Manager
Joined: 02 Jan 2007
Posts: 208
Followers: 2

Kudos [?]: 3 [0], given: 0

I go with B.

let the total no. of switches = 100
so defective (or lets say d) = 20
of these 4/5 get rejected, so
& nrd (non-rejected defectives) =4 (20-16 ie 4/5 of 20)..........i

Total Non-defective switches (or n) = 80
1/20 of these are rejected by mistake, thats
mr (mistakenly rejected) = 4
so good switches sold = 76........................ii

With this we now we need to find out how many switches sold
and how many rejectes sold.

Total sold = 80 (adding i & ii)
of these defective = 4 ......from i

4/80*100 = 5%
Intern
Joined: 11 Feb 2007
Posts: 30
Followers: 0

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

i get 5% too. good explanation.
Manager
Joined: 28 Feb 2007
Posts: 197
Location: California
Followers: 2

Kudos [?]: 6 [0], given: 0

Re: Please, help to solve not concise question!!! [#permalink]  29 Mar 2007, 19:43
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 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%

Rejected defective switches = 1/5 x 4/5 = 4/25
Accepted defective swicthes = 1/5 x 1/5 = 1/25

Rejected good switches = 4/5 x 1/20 = 1/25
Accepted good switched = 4/5 x 19/20 = 19/25

Since all accepted switches are sold so total switches sold = 1/25 + 19/25 = 4/5

required answer = 1/25 / 4/5 = 1/20 = 5%
Senior Manager
Joined: 13 Mar 2007
Posts: 295
Location: Russia, Moscow
Followers: 2

Kudos [?]: 22 [0], given: 0

GMAT Club Legend
Joined: 07 Jul 2004
Posts: 5077
Location: Singapore
Followers: 22

Kudos [?]: 186 [0], given: 0

Assume total 100 switches produced.

(100)*(1/5) = 20 switches are defective

4/5*(20) = 16 swtitches are rejected

1/20*(80) = 4 switches are rejected by mistake.

# of switches sold = 76 + 4 = 80
# of defects sold = 4
% = 4/80 * 100% = 5%
Similar topics Replies Last post
Similar
Topics:
4 One-fifth of the batteries produced by an upstart factory are defectiv 4 26 Nov 2014, 06:56
One-fifth of the light switches produced by a certain 2 27 Mar 2008, 18:29
One-fifth of the light switches produced by a certain 10 28 Nov 2007, 12:37
One-fifth of the light switches produced by a certain 7 07 May 2006, 09:23
One-fifth of the light switches produced by a cer tain 2 15 Oct 2005, 22:17
Display posts from previous: Sort by