BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

500 ps

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 269
Joined: Sun Apr 01, 2007 5:41 am

500 ps

by dunkin77 » Wed Apr 04, 2007 11:13 am
Hi,

The correct answer is B) ..can anyone explain? thx!

One-fifth of the light switches produced by a certain 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%
Top
Source: — Problem Solving |
User avatar
Legendary Member
Posts: 986
Joined: Wed Dec 20, 2006 11:07 am
Location: India
Thanked: 51 times
Followed by:1 members

Re: 500 ps

by gabriel » Wed Apr 04, 2007 12:53 pm
dunkin77 wrote:Hi,

The correct answer is B) ..can anyone explain? thx!

One-fifth of the light switches produced by a certain 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%

the darkened sentence is incomplete ... chk it out ...
Top
Master | Next Rank: 500 Posts
Posts: 269
Joined: Sun Apr 01, 2007 5:41 am

by dunkin77 » Wed Apr 04, 2007 1:23 pm
Oops - sorry! here you go - thanks!

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%
Top
Senior | Next Rank: 100 Posts
Posts: 46
Joined: Sun Mar 04, 2007 6:27 am

by Tame the CAT » Wed Apr 04, 2007 7:30 pm
I did not get the same answer, I got 4%.

For my setup, please look at the attachment. I thought I had a good grasp of this. Am I missing something?
Attachments
Overlapping Table.xls
(14.5 KiB) Downloaded 151 times
Top
Legendary Member
Posts: 559
Joined: Tue Mar 27, 2007 1:29 am
Thanked: 5 times
Followed by:2 members

by Cybermusings » Thu Apr 05, 2007 1:18 am
Let total number of switches produced be y. Therefore y/5 are defective. 4/5 of y/5 = 4y/25 are rejected.

y/5 - 4y/25 = y/25 of switches which are defective (but not rejected) are sold.

Total number of non-defective switches = 4y/5. Ones rejected = 1/20 of 4y/5 = 4y/100 = y/25 are rejected

Total rejected = 4y/25 + y/25 = 5y/25 = y/5. Therefore total sold = 4y/5

Therefore percent of the switches sold by the factory that are defective =( (y/25) / (4y/5) ) * 100

= 5%
Top
Post new topic Post Reply
• Page 1 of 1