Stereos

This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 435
Joined: Wed Nov 16, 2011 7:27 am
Thanked: 48 times
Followed by:16 members

Stereos

by alex.gellatly » Mon May 21, 2012 7:06 pm
Company S produces two kinds of stereos: basic and deluxe. Of the stereos produced by Company X last month, 2/3 were basic and the rest were deluxe. If it takes 7/5 as many hours to produce a deluxe stereo as it does to produce a basic stereo, then the number of hours it took to produce the deluxe stereos last month was what fraction of the total number of hours it took to produce all the stereos?

A. 7/17
B. 14/31
C. 7/15
D. 17/35
E. 1/2

Thanks

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3835
Joined: Fri Apr 02, 2010 10:00 pm
Location: Milpitas, CA
Thanked: 1854 times
Followed by:523 members
GMAT Score:770

by Anurag@Gurome » Mon May 21, 2012 7:15 pm
alex.gellatly wrote:Company S produces two kinds of stereos: basic and deluxe. Of the stereos produced by Company X last month, 2/3 were basic and the rest were deluxe. If it takes 7/5 as many hours to produce a deluxe stereo as it does to produce a basic stereo, then the number of hours it took to produce the deluxe stereos last month was what fraction of the total number of hours it took to produce all the stereos?

A. 7/17
B. 14/31
C. 7/15
D. 17/35
E. 1/2

Thanks
Let us assume that total stereos = 15
Then number of basic stereos = 2/3 of total = (2/3) * 15 = 10
and Number of deluxe stereos = 1/3 of total = (1/3) * 15 = 5

If time needed to produce one Deluxe stereo is 1 unit than time needed to produce one Basic stereo would be 7/5 units.
Total time for Basic = 10 * 1 = 10
Total time for Deluxe = 5 * (7/5) = 7
So, total time for both = 10 + 7 = 17
Therefore, deluxe/total = [spoiler]7/17[/spoiler]

The correct answer is A.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/

User avatar
Legendary Member
Posts: 1239
Joined: Tue Apr 26, 2011 6:25 am
Thanked: 233 times
Followed by:26 members
GMAT Score:680

by sam2304 » Mon May 21, 2012 7:30 pm
Given 2/3 were basic and rest were deluxe stereos.

Consider the number as it is, 2 basic and 1 deluxe stereo.

it takes 7/5 as many hours to produce a deluxe stereo as it does to produce a basic stereo.

Time taken for basic be b, then d = 7b/5
= d/b => 7/5

Time for basic is 5 hours and deluxe is 7 hours. We considered 2 deluxe and 1 basic stereo.

Total time for basic = 10 hours
total time for deluxe = 7 hours
Deluxe stereo hours/total hours = 7/(10+7)

IMO A.
Getting defeated is just a temporary notion, giving it up is what makes it permanent.
https://gmatandbeyond.blogspot.in/

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 7223
Joined: Sat Apr 25, 2015 10:56 am
Location: Los Angeles, CA
Thanked: 43 times
Followed by:29 members

by Scott@TargetTestPrep » Thu Jan 11, 2018 2:08 pm
alex.gellatly wrote:Company S produces two kinds of stereos: basic and deluxe. Of the stereos produced by Company X last month, 2/3 were basic and the rest were deluxe. If it takes 7/5 as many hours to produce a deluxe stereo as it does to produce a basic stereo, then the number of hours it took to produce the deluxe stereos last month was what fraction of the total number of hours it took to produce all the stereos?

A. 7/17
B. 14/31
C. 7/15
D. 17/35
E. 1/2
We can let the total number of stereos = 12; thus, 8 are basic and 4 are deluxe.

We can let the number of hours to produce a basic stereo = 10, and thus it takes 7/5 x 10 = 14 hours to produce a deluxe stereo.

So the number of hours to produce the deluxe stereos last month was 14 x 4 = 56 hours, and the number of hours to produce the basic stereos was 8 x 10 = 80 hours.

Thus, the time to make the deluxe stereos was 56/(56 + 80) = 56/136 = 7/17 of the total time taken to produce all stereos.

Answer: A