NEW HERE? LEARN MORE
closeclose
Last visit was: 24 Apr 2024, 11:02 It is currently 24 Apr 2024, 11:02
Decision Tracker
My Rewards
New posts
New comers' posts

Close
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
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

Six machines, each working at the same constant rate

SORT BY:
Date
Kudos
   1   2 
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92902
Own Kudos [?]: 618783 [0]
Given Kudos: 81588
Send PM
CAT Tests Forum Quiz Mode
Re: Six machines, each working at the same constant rate [#permalink] New post   07 Dec 2022, 02:13
Expert Reply
Schachfreizeit wrote:
Bunuel wrote:
Six machines, each working at the same constant rate, together can complete a certain job in 12 days. How many additional machines, each working at the same constant rate, will be needed to complete the job in 8 days?
A. 2
B. 3
C. 4
D. 6
E. 8

Let \(x\) be the time needed for 1 machine to complete the job, so rate of one machine is \(\frac{1}{x}\) (rate is the reciprocal of time) --> rate of 6 machines would be \(\frac{6}{x}\).

As \(job=time*rate\) --> \(1=12*\frac{6}{x}\) --> \(x=72\) days needed for 1 machine to complete the job.

To complete the job in 8 days \(\frac{72}{8}=9\) machines are needed.


Difference: 9-6=3.

Answer: B.


so if one machine would need 60 min, so 1/60 to get the job done, 6 machines would need 10 min, bc 6/60=1/10?
I don't understand the equation: 1=12*(6/x). Why does 12*(6/x) equals 1?


1 there is the number of jobs done but ignore the formula for a moment.

If 6 machines need 12 days to complete a certain job, then 1 machine will need 6 times the days, so 6*12 = 72 days, no?
avatar
B
Dhruva2000
Intern
Intern
Joined: 19 Jan 2022
Posts: 4
Own Kudos [?]: 0 [0]
Given Kudos: 59
Send PM
Re: Six machines, each working at the same constant rate [#permalink] New post   04 Sep 2023, 04:44
#workers/Rate of worker = Proportion method.

6/(1/12)=x/(1/8)
6*12 = x*8
x=9
therefore
9-6= 3 (B is the correct option)
User avatar
S
Paras96
Director
Director
Joined: 11 Sep 2022
Posts: 501
Own Kudos [?]: 151 [0]
Given Kudos: 2
Location: India
Paras: Bhawsar
GMAT 1: 590 Q47 V24
GMAT 2: 580 Q49 V21
GMAT 3: 700 Q49 V35
GPA: 3.2
WE:Project Management (Other)
Send PM
Re: Six machines, each working at the same constant rate [#permalink] New post   09 Sep 2023, 10:10
Six machines, each working at the same constant rate, together can complete a certain job in 12 days. How many additional machines, each working at the same constant rate, will be needed to complete the Job in 8 days?
SOLUTION:- (M1D1) = (M2D2)
6 * 12 = M2 * 8 ; where M2 is the number of machines required to complete the job in 8 days
M2 = 9
Addition machines required = 9 - 6 = 3
Hence B
GMAT Club Bot
gmatclubot
Re: Six machines, each working at the same constant rate [#permalink]
09 Sep 2023, 10:10
   1   2 
Moderators:
Bunuel
Math Expert
92902 posts
yashikaaggarwal
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions