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:

Two women, A and B working separately can mow a field in 8 [#permalink]

Show Tags

28 Jun 2010, 08:01

1

This post received KUDOS

7

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

65% (hard)

Question Stats:

51% (02:13) correct
49% (02:08) wrong based on 63 sessions

HideShow timer Statistics

Two women, A and B working separately can mow a field in 8 and 12 hrs respectively. If they work together in stretches on 1 hr alternately, A beginning at 9:00 AM, when will the mowing be finished?

Can anybody plz explain the best way to solve such problems?

Two women, A and B working separately can mow a field in 8 and 12 hrs respectively. If they work together in stretches on 1 hr alternately, A beginning at 9:00 AM, when will the mowing be finished?

Can anybody plz explain the best way to solve such problems?

In 1 hour A does \(\frac{1}{8}=\frac{3}{24}\)th of the whole job and B \(\frac{1}{12}=\frac{2}{24}\)th of the whole job (common denimnator makes the following calculations easier). So in 2 hours they do \(\frac{3}{24}+\frac{2}{24}=\frac{5}{24}\)th of the whole job (so at this stage we know that time needed to do the whole job will be less than 5 2-hour periods or 10 hours, as \(5*\frac{5}{24}=\frac{25}{24}>1\)).

Now in 8 hours (4 two hour periods) they do \(4*\frac{5}{24}=\frac{20}{24}\)th of the whole job. Then will be A's turn and by the end of 9 hours \(\frac{20}{24}+\frac{3}{24}=\frac{23}{24}\)th of the job will be done and \(\frac{1}{24}\)th will be left, which can be done by B (as it's B's turn now) in 1/2hours (30 minutes). So total time \(8+1+\frac{1}{2}=9\frac{1}{2}\), hence they will finish at \(9:00AM+9\frac{1}{2}=18:30PM\).

Thanks Bunuel for the detailed solution, can u pls advise why we calculated for 2 hrs?

2 hours is 1 cycle - a period of time when both A and B worked once. As long as we know what part of the job is done in one cycle we can find in which range to look for the correct answer. We had that the period of time must be less than 5 cycles (10 hours) and then we started calculating directly for 4 cycles, which saved us some time.
_________________

Thanks Bunuel for the detailed solution, can u pls advise why we calculated for 2 hrs?

2 hours is 1 cycle - a period of time when both A and B worked once. As long as we know what part of the job is done in one cycle we can find in which range to look for the correct answer. We had that the period of time must be less than 5 cycles (10 hours) and then we started calculating directly for 4 cycles, which saved us some time.

Thanks Bunuel, One more question my understanding for "If they work together in stretches on 1 hr alternately," sentence was, they will work alternatively lets say A will work at 9:00 AM and B will start at 10:00AM. If my understanding is correct the how come 9th hr will come for A?
_________________

_________________ If you like my post, consider giving me a kudos. THANKS!

Thanks Bunuel, One more question my understanding for "If they work together in stretches on 1 hr alternately," sentence was, they will work alternatively lets say A will work at 9:00 AM and B will start at 10:00AM. If my understanding is correct the how come 9th hr will come for A?

Hi,

A goes first, so A does the 1st hour, 3rd hour, 5th hour, 7th hour, 9th hour, ...

Thanks Bunuel, One more question my understanding for "If they work together in stretches on 1 hr alternately," sentence was, they will work alternatively lets say A will work at 9:00 AM and B will start at 10:00AM. If my understanding is correct the how come 9th hr will come for A?

Hi,

A goes first, so A does the 1st hour, 3rd hour, 5th hour, 7th hour, 9th hour, ...

Thanks skovinsky, now I got it
_________________

_________________ If you like my post, consider giving me a kudos. THANKS!

mmm... the working alternately thing is kind of a pain.

So in the first hour A did 1/8th of the job, & in the 2nd hour B did 1/12th of the job. In 2 hours, they did 5/24 of the job together. Meaning in 8 hours they would have completed (5/24)X4=20/24.

In the 9th hour, A is on shift again & completes 1/8th (or in other words, 3/24th) of the job, so we're now that 23/24. In the 10th hour, B completes the remainder 1/24th. We know B can do 1/12th in 1 hour, so she'll only take half the hour to complete 1/24th of the job.

We do some counting with our fingers & see that it takes 9.5 hours. So starting at 0900 (9am in civilian time), we would complete the job at 18:30 or 6:30pm.

Kind of a pain in the ass but doable in 2 minutes.

Re: Two women, A and B working separately can mow a field in 8 [#permalink]

Show Tags

28 Jul 2013, 00:46

Two women, A and B working separately can mow a field in 8 and 12 hrs respectively. If they work together in stretches on 1 hr alternately, A beginning at 9:00 AM, when will the mowing be finished?

HI Bunnel Please clarify me where I have gone wrong

Rate A-1/8 Rate B-1/12

let say A works for 4 hour and rate is 1/8 so total job done = 1/8*4=1/2 Similarly let say B works for 6 hour and rate is 1/12 so total job done=1/12*6=1/2

So both can finish the work in 10 hours if they work alternatively. 9.00 am+10 hour=19.00pm answer

Two women, A and B working separately can mow a field in 8 and 12 hrs respectively. If they work together in stretches on 1 hr alternately, A beginning at 9:00 AM, when will the mowing be finished?

HI Bunnel Please clarify me where I have gone wrong

Rate A-1/8 Rate B-1/12

let say A works for 4 hour and rate is 1/8 so total job done = 1/8*4=1/2 Similarly let say B works for 6 hour and rate is 1/12 so total job done=1/12*6=1/2

So both can finish the work in 10 hours if they work alternatively. 9.00 am+10 hour=19.00pm answer

Where i have gone wrong..............

Rgds Prasannajeet

I think you misinterpreted the question. A and B work in shifts: A goes first and works for 1 hour, then goes B and works for 1 hour, ... Thus, for this scenario it's not possible A to work 4 hours and B 6 hours.
_________________

Re: Two women, A and B working separately can mow a field in 8 [#permalink]

Show Tags

10 Aug 2014, 06:53

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

Re: Two women, A and B working separately can mow a field in 8 [#permalink]

Show Tags

12 Oct 2015, 08:42

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

Re: Two women, A and B working separately can mow a field in 8 [#permalink]

Show Tags

09 Nov 2015, 13:37

Bunuel wrote:

prasannajeet wrote:

Two women, A and B working separately can mow a field in 8 and 12 hrs respectively. If they work together in stretches on 1 hr alternately, A beginning at 9:00 AM, when will the mowing be finished?

HI Bunnel Please clarify me where I have gone wrong

Rate A-1/8 Rate B-1/12

let say A works for 4 hour and rate is 1/8 so total job done = 1/8*4=1/2 Similarly let say B works for 6 hour and rate is 1/12 so total job done=1/12*6=1/2

So both can finish the work in 10 hours if they work alternatively. 9.00 am+10 hour=19.00pm answer

Where i have gone wrong..............

Rgds Prasannajeet

I think you misinterpreted the question. A and B work in shifts: A goes first and works for 1 hour, then goes B and works for 1 hour, ... Thus, for this scenario it's not possible A to work 4 hours and B 6 hours.

hey Bunuel,

thanks for the solution,

I just have one questions

if the rate came to 5/25 instead of 5/24, would the answer me 10 hours?

I stopped my solution at time = 24/5 = about 9.8 hours. Not sure what alerts us to solve further for the breakdown.

Re: Two women, A and B working separately can mow a field in 8 [#permalink]

Show Tags

09 Nov 2015, 21:02

add the answers to the question the answer should be 18:30 let's assume that the total work is 48 the A will do in 1 hour 6 parts of the work, B will do 4 parts of the work 2 hours - 10 parts of the work 4 hours - 20 parts 6 hours - 30 parts 8 hours - 40 parts 9 hours - 46 parts 9.5 hours - 48 parts

started at 9AM + 9.5hr = 18:30

gmatclubot

Re: Two women, A and B working separately can mow a field in 8
[#permalink]
09 Nov 2015, 21:02

Happy New Year everyone! Before I get started on this post, and well, restarted on this blog in general, I wanted to mention something. For the past several months...

It’s quickly approaching two years since I last wrote anything on this blog. A lot has happened since then. When I last posted, I had just gotten back from...

Happy 2017! Here is another update, 7 months later. With this pace I might add only one more post before the end of the GSB! However, I promised that...