It is currently 26 Jun 2017, 22:22

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

m6 ques 21

Author Message
Senior Manager
Joined: 19 Nov 2007
Posts: 459

Show Tags

06 Apr 2010, 19:10
A furniture manufacturer has two machines, but only one can be used at a time. Machine A is utilized during the first shift and Machine B during the second shift, while both work half of the third shift. If Machine A can do the job in 12 days working two shifts and Machine B can do the job in 15 days working two shifts, how many days will it take to do the job with the current work schedule?

* 14
* 13
* 11
* 9
* 7

In this question, shouldn't Machine A's no. of days to do the job working 1.5 shifts be 18?
Because working 2 shifts, its 12 and working 1 shift its 24.
Please tell me what am I missing here
.
_________________

-Underline your question. It takes only a few seconds!
-Search before you post.

Manager
Joined: 29 Oct 2009
Posts: 199
Concentration: General Management, Sustainability
WE: Consulting (Computer Software)

Show Tags

07 Apr 2010, 09:13
This is my approach.
A can do the job in 12 days working two shifts => Number of shifts A takes to complete the job is = 2*12 = 24 shifts.
Work done by A per shift = 1/24

B can do the job in 15 days working two shifts =>Number of shifts B takes to complete the job is = 2*15 = 30 shifts.
Work done by B per shift = 1/30

Machine A is utilized during the first shift and Machine B during the second shift, while both work half of the third shift => Per day there are three shifts.

First shift A is utilized => work done = 1/24
Second shift B is utilized => work done = 1/30
Work done by A in half shift + Work done by B in half shift = 1/(2*24) + 1/(2*30) = 1/48+1/60.

Total work done in a day (shift1+shift2+shift3) = 1/24+1/30+(1/48+1/60)
Solving this gives us 9/80 as the work done per day.
So number of days required to complete the job = 80/9 which is nearly equal to 9 days.

Re: m6 ques 21   [#permalink] 07 Apr 2010, 09:13
Similar topics Replies Last post
Similar
Topics:
M21 Ques36 Doubt 1 30 Nov 2009, 23:59
5 M6 5 10 Dec 2008, 14:48
V06 Number 21 4 11 Oct 2008, 10:28
32 M21 #28 26 13 Jun 2014, 07:23
15 combi ques (m08q04) 19 02 Nov 2013, 13:42
Display posts from previous: Sort by

m6 ques 21

Moderator: Bunuel

 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®.