Check GMAT Club Decision Tracker for the Latest School Decision Releases https://gmatclub.com/AppTrack

 It is currently 22 May 2017, 23:30

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

It takes printer A 4 more minutes than printer B to print 40

Author Message
TAGS:

Hide Tags

Manager
Joined: 13 Aug 2009
Posts: 148
WE 1: 4 years in IT
Followers: 1

Kudos [?]: 269 [1] , given: 7

It takes printer A 4 more minutes than printer B to print 40 [#permalink]

Show Tags

15 Feb 2010, 00:21
1
KUDOS
3
This post was
BOOKMARKED
00:00

Difficulty:

65% (hard)

Question Stats:

65% (03:37) correct 35% (03:25) wrong based on 78 sessions

HideShow timer Statistics

It takes printer A 4 more minutes than printer B to print 40 pages. Working together, the two printers can print 50 pages in 6 minutes. How long will it take printer A to print 80 pages?

A. 12
B. 18
C. 20
D. 24
E. 30

OPEN DISCUSSION OF THIS QUESTION IS HERE: it-takes-printer-a-4-more-minutes-than-printer-b-to-print-98479.html
[Reveal] Spoiler: OA

Last edited by Bunuel on 29 Sep 2013, 09:26, edited 1 time in total.
Renamed the topic, edited the question and added the OA.
VP
Status: There is always something new !!
Affiliations: PMI,QAI Global,eXampleCG
Joined: 08 May 2009
Posts: 1335
Followers: 17

Kudos [?]: 254 [1] , given: 10

Re: work rate ps--plz solve [#permalink]

Show Tags

15 Feb 2010, 06:03
1
KUDOS
working together A and B can finish typing 40 pages = (6/ 50) * 40 = 24/5 mints.

Per unit work done by A and B is individually denoted by 1/A and 1/(A - 4) respectively.

Now Substituting all in the form of an equation,we have

1/A + 1/(A -4) = 5 / 24

We obtain a quadratic equation as ,

5A^2 - 68A + 96 = 0

Solving this equation A = 12 mints. Hence for 80 pages 12 * 2 = 24 mints.

Thank you and have fun in 'GMATLAND' as we ALL ARE having.
_________________

Visit -- http://www.sustainable-sphere.com/
Promote Green Business,Sustainable Living and Green Earth !!

Last edited by amit2k9 on 15 Feb 2010, 10:41, edited 1 time in total.
Manager
Joined: 10 Jan 2010
Posts: 186
Location: Germany
Concentration: Strategy, General Management
Schools: IE '15 (M)
GPA: 3
WE: Consulting (Telecommunications)
Followers: 2

Kudos [?]: 30 [0], given: 7

Re: work rate ps--plz solve [#permalink]

Show Tags

15 Feb 2010, 08:42
50 pages = 6 mins
40 pages = (6/50)*40 = \frac{24}{5}mins
40 pages = a + b (but a = b + 4mins)

Since each printer can do 1/a or 1/b work per unit, we can solve the equation:

$$1/a + 1/(a-4)= 5/24$$

Solved - like amit2k9 did - with a quadratic equation:

$$5a^2 - 68a + 96 = 0$$

$$a^2 - 68a/5 + 96/5 = 0$$

$$(a-8/5)*(a-60/5) = 0$$

$$a = 8/5 or a = 12$$ --> only 12 works

Hence, a needs 12 mins for 40 pages --> 24 mins = 80 pages

GMAT Instructor
Joined: 04 Jul 2006
Posts: 1263
Followers: 29

Kudos [?]: 307 [0], given: 0

Re: work rate ps--plz solve [#permalink]

Show Tags

15 Feb 2010, 11:20
MSoS wrote:
50 pages = 6 mins
40 pages = (6/50)*40 = \frac{24}{5}mins
40 pages = a + b (but a = b + 4mins)

Since each printer can do 1/a or 1/b work per unit, we can solve the equation:

$$1/a + 1/(a-4)= 5/24$$

Solved - like amit2k9 did - with a quadratic equation:

$$5a^2 - 68a + 96 = 0$$

$$a^2 - 68a/5 + 96/5 = 0$$

$$(a-8/5)*(a-60/5) = 0$$

$$a = 8/5 or a = 12$$ --> only 12 works

Hence, a needs 12 mins for 40 pages --> 24 mins = 80 pages

If you hate factoring, you could reason that the LCM of a and a - 4 is 24 and thus suspect that a is 12
Manager
Status: Getting ready for the internship summer
Joined: 07 Jun 2009
Posts: 51
Location: Rochester, NY
Schools: Simon
WE 1: JPM - Treasury
Followers: 0

Kudos [?]: 27 [0], given: 23

Re: work rate ps--plz solve [#permalink]

Show Tags

15 Feb 2010, 16:41
If you don't want to deal with quadratics this question is a good choice to just pick numbers.

$$\frac{1}{x} + \frac{1}{x+4} = \frac{5}{24}$$

$$\frac{1}{12} + \frac{1}{8} = \frac{5}{24}$$

x = 12, so the answer is 24.
Director
Joined: 03 Aug 2012
Posts: 897
Concentration: General Management, General Management
GMAT 1: 630 Q47 V29
GMAT 2: 680 Q50 V32
GPA: 3.7
WE: Information Technology (Investment Banking)
Followers: 24

Kudos [?]: 764 [0], given: 322

Re: work rate ps--plz solve [#permalink]

Show Tags

28 Sep 2013, 10:40
40/t + 40/(t+4) = 50/6

5t^2 -28t - 96 = 0

Substitute t=8 it satisfies

Hence time for 20 pages (t+4) =12
Time for 40 is 24

Hence (D) !
_________________

Rgds,
TGC!
_____________________________________________________________________
I Assisted You => KUDOS Please
_____________________________________________________________________________

Math Expert
Joined: 02 Sep 2009
Posts: 38799
Followers: 7715

Kudos [?]: 105821 [0], given: 11589

Re: It takes printer A 4 more minutes than printer B to print 40 [#permalink]

Show Tags

29 Sep 2013, 09:26
Let the time needed to print 40 pages for printer A be $$a$$ minutes, so for printer B it would be $$a-4$$ minutes.

The rate of A would be $$rate=\frac{job}{time}=\frac{40}{a}$$ pages per minute and the rate of B $$rate=\frac{job}{time}=\frac{40}{a-4}$$ pages per minute.

Their combined rate would be $$\frac{40}{a}+\frac{40}{a-4}$$ pages per minute. Also as "two printers can print 50 pages in 6 minutes" then their combined rate is $$rate=\frac{job}{time}=\frac{50}{6}$$, so $$\frac{40}{a}+\frac{40}{a-4}=\frac{50}{6}$$.

$$\frac{40}{a}+\frac{40}{a-4}=\frac{50}{6}$$ --> $$\frac{1}{a}+\frac{1}{a-4}=\frac{5}{24}$$. At this point we can either try to substitute the values from answer choices or solve quadratic equation. Remember as we are asked to find time needed for printer A to print $$80$$ pages, then the answer would be $$2a$$ (as $$a$$ is the time needed to print $$40$$ pages). Answer D works: $$2a=24$$ --> $$a=12$$ --> $$\frac{1}{12}+\frac{1}{8}=\frac{5}{24}$$.

OPEN DISCUSSION OF THIS QUESTION IS HERE: it-takes-printer-a-4-more-minutes-than-printer-b-to-print-98479.html
_________________
Re: It takes printer A 4 more minutes than printer B to print 40   [#permalink] 29 Sep 2013, 09:26
Similar topics Replies Last post
Similar
Topics:
1 A particular printer can print 96 pages in 25 minutes. How many minute 5 19 Apr 2017, 15:58
1 Printer A and Printer B can each print 1 ⁄4 page per second. How long 3 11 Jan 2016, 21:26
2 A certain business printer can print 40 characters per second, which 3 19 Apr 2016, 14:00
59 Printer a takes 40 more minutes to print the pages of a book 17 09 Apr 2017, 16:08
71 It takes printer A 4 more minutes than printer B to print 40 32 07 Nov 2016, 11:48
Display posts from previous: Sort by