GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 21 Jun 2018, 03:35

### 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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# work

 post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
Senior Manager
Joined: 05 Oct 2008
Posts: 258
work [#permalink]

### Show Tags

25 Jan 2009, 12:10
6 machines take 12 days to complete a job. How many more machines will be needed to complete the job in 8 days?

2
3
4
5
6

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
GMAT Tutor
Joined: 24 Jun 2008
Posts: 1345
Re: work [#permalink]

### Show Tags

Updated on: 25 Jan 2009, 15:56
The job requires 6*12 = 72 total days of machine work. So, one machine would do the job in 72 days, two machines in 36 days, three machines would need 24 days, etc. To do the job in 8 days, we'd need 9 machines in total, or 3 additional machines.
_________________

GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com

Originally posted by IanStewart on 25 Jan 2009, 12:19.
Last edited by IanStewart on 25 Jan 2009, 15:56, edited 1 time in total.
wrote 'hours' instead of 'days'!
Intern
Joined: 24 Jan 2009
Posts: 18
Re: work [#permalink]

### Show Tags

25 Jan 2009, 13:22
1
If 6 machines take 12 days to complete the task, one machine takes 72 days. Let X be number of machines and d the number of days:
$$\frac{x}{72}=\frac{1}{d}$$

What you want is for d to equal 8, so X must be nine and you'll need 3 more machines.
Answer B
----------
All Day
_________________

All Day

Intern
Joined: 19 Jan 2009
Posts: 16
Re: work [#permalink]

### Show Tags

27 Jan 2009, 10:39
6 machines take 12 days to complete a job. How many more machines will be needed to complete the job in 8 days?

2
3
4
5
6

This question is on inverse proportions.
Its btw number of machines and days.

so md = k ( constant)

6x12 = m x 8

6 x 12 / 8 = m

9 = m

how many more = 9 - 6 = 3

so the answer is B.

http://www.graduatetutor.com

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Re: work   [#permalink] 27 Jan 2009, 10:39
Display posts from previous: Sort by

# work

 post reply Question banks Downloads My Bookmarks Reviews Important topics

Moderator: chetan2u

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne 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®.