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.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

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

Show Tags

31 Oct 2007, 23:44

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

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?

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?

12 18 20 24 30

Lets say printer B takes b minutes to print 40 pages then A will need (b+4) minutes to print 40 pages. Together they need 6 mniutes to print 50 pages.

40/b + 40/(b+4) = 50/6
24(2b+4) = 5(b pow 2+ 4b)

Solving quadratic equation gives b = 8 or -2.4, for sure - time is not feasible. Therefore A needs 8+4 = 12 minutes to print 40 pages hence 24 minutes to print 80 pages.

I had the same setup equation, but that quadratic equation is BRUTAL.

yup thats why i posted the question.. to see if anyone else had another approach to avoid quadratic eqn

so far nil..

You could work backward from the answer choices. Start with C:

Suppose A takes 20 minutes for 80 pages. Then A's rate is 4 pages per minute, or 40 pages in 10 minutes. B's rate is 40 pages in 6 minutes, or 40/6. Combined, their rates are 4 + (40/6) = 64/6, which is greater than 50/6. So the rate for A yielded by this answer choice is too high. A must take more than 20 minutes to print 80 pages.

So move on to D. A's rate is 80/24 or 10/3 pages per minute. A takes 12 minutes for 40 pages, so B takes 8, and B's rate is 40/8 = 5. Their combined rate is 10/3 + 5 = 10/3 + 15/3 = 25/3 = 50/6. There's the answer.

I had the same setup equation, but that quadratic equation is BRUTAL.

yup thats why i posted the question.. to see if anyone else had another approach to avoid quadratic eqn

so far nil..

You could work backward from the answer choices. Start with C:

Suppose A takes 20 minutes for 80 pages. Then A's rate is 4 pages per minute, or 40 pages in 10 minutes. B's rate is 40 pages in 6 minutes, or 40/6. Combined, their rates are 4 + (40/6) = 64/6, which is greater than 50/6. So the rate for A yielded by this answer choice is too high. A must take more than 20 minutes to print 80 pages.

So move on to D. A's rate is 80/24 or 10/3 pages per minute. A takes 12 minutes for 40 pages, so B takes 8, and B's rate is 40/8 = 5. Their combined rate is 10/3 + 5 = 10/3 + 15/3 = 25/3 = 50/6. There's the answer.

Nice approach, far better than solving equations
But i think time taken solving equations and going through answer choices is almost same even starting from A may take much more time.

** One has to be careful when comparing 25/3 to 50/6 because one is expecting an answer that matches with 50/6 while answer is 25/3 that can lead to a wrong decision taken quickly

I had the same setup equation, but that quadratic equation is BRUTAL.

yup thats why i posted the question.. to see if anyone else had another approach to avoid quadratic eqn

so far nil..

You could work backward from the answer choices. Start with C:

Suppose A takes 20 minutes for 80 pages. Then A's rate is 4 pages per minute, or 40 pages in 10 minutes. B's rate is 40 pages in 6 minutes, or 40/6. Combined, their rates are 4 + (40/6) = 64/6, which is greater than 50/6. So the rate for A yielded by this answer choice is too high. A must take more than 20 minutes to print 80 pages.

So move on to D. A's rate is 80/24 or 10/3 pages per minute. A takes 12 minutes for 40 pages, so B takes 8, and B's rate is 40/8 = 5. Their combined rate is 10/3 + 5 = 10/3 + 15/3 = 25/3 = 50/6. There's the answer.