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:

Mr. Verma can do a job in 10 days. A helper joins him after 3 days, an [#permalink]

Show Tags

13 Jun 2017, 10:09

3

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

25% (medium)

Question Stats:

80% (01:50) correct 20% (02:00) wrong based on 103 sessions

HideShow timer Statistics

Mr. Verma can do a job in 10 days. A helper joins him after 3 days, and together they work for 4 days to complete the task. How many days would it take the helper to do the job alone?

a) 3 b) \(5 \frac{5}{7}\) c) 6 d) 7 e) \(13\frac{1}{3}\)

Re: How many days would it take the helper to do the job alone? [#permalink]

Show Tags

13 Jun 2017, 10:18

1

This post was BOOKMARKED

Mr Verma can do a job in 10 days. His per day work = 1/10 So in 3 days, he can do alone = 3/10 of the work. Remaining work = 1 - 3/10 = 7/10

Now Mr Verma and helper can do 7/10 of the work in 4 days. That means together, they can do complete work in = 4*10/7 = 40/7 days So together, per day work of Mr Verma and helper combined = 7/40

This means work of helper per day = 7/40 - 1/10 (1/10 is per day work of Mr Verma) = 3/40

This means helper can do complete work in 40/3 days.. Or 13 1/3 days.

Mr. Verma can do a job in 10 days. A helper joins him after 3 days, and together they work for 4 days to complete the task. How many days would it take the helper to do the job alone?

a) 3 b) \(5 \frac{5}{7}\) c) 6 d) 7 e) \(13\frac{1}{3}\)

This can be done with almost no algebra.

So, when a helper joins there are 7 days of work left to be done. If the helper's rate was equal to Mr. Verma's rate, then the job will be done in 3.5 days. Since the actual time (4 days) is longer than that, then the helper's rate must be lower than that of Mr. Verma's. Mr. Verma can do the job in 10 days, so the helper will take longer. Only E fits.

Re: Mr. Verma can do a job in 10 days. A helper joins him after 3 days, an [#permalink]

Show Tags

29 Jun 2017, 02:06

1

This post received KUDOS

For me, easiest way to do work/ rate problems is by taking the LCM or multiple of all the given numbers in a question and assume it to be total number of units of work to be done. This eliminates the chances of making error while doing calculation with fractions.

In this question, we are given 3 numbers, 10, 3 and 4. Let's say total units of work to be done is 60 (60 is a multiple of 10, 3 and 4).

Mr. Verma will do 6 units per day (Mr Verma's rate of work) to do the given task in 10 days. He works for 3 days alone so he'll do 18 units of work. Then helper joins. Work to be done is 60-18 = 42 units. Both complete the remaining job in 4 days so combined rate is 10.5 units per day. Work rate of helper will be, 10-5-6 = 4.5 units per day.

At this rate if worker has to do 60 units of work alone, he'll take 60/4.5 = 40/3 days or 13 1/3 days.

Mr. Verma can do a job in 10 days. A helper joins him after 3 days, and together they work for 4 days to complete the task. How many days would it take the helper to do the job alone?

a) 3 b) \(5 \frac{5}{7}\) c) 6 d) 7 e) \(13\frac{1}{3}\)

We are given that Mr. Verma can complete a job in 10 days; thus, the rate of Mr. Verma is 1/10.

So, after 3 days, he has completed 3/10 of the job.

When he works with the helper, they complete 7/10 of the job in 4 days, or work at a rate of (7/10)/4 = 7/40.

If we let the rate of the helper = 1/x, then:

1/10 + 1/x = 7/40

Multiplying the entire equation by 40x, we have:

4x + 40 = 7x

40 = 3x

x = 40/3 = 13 ⅓

Answer: E
_________________

Jeffery Miller Head of GMAT Instruction

GMAT Quant Self-Study Course 500+ lessons 3000+ practice problems 800+ HD solutions

Re: Mr. Verma can do a job in 10 days. A helper joins him after 3 days, an [#permalink]

Show Tags

12 Aug 2017, 21:12

rosmann wrote:

Mr. Verma can do a job in 10 days. A helper joins him after 3 days, and together they work for 4 days to complete the task. How many days would it take the helper to do the job alone?

a) 3 b) \(5 \frac{5}{7}\) c) 6 d) 7 e) \(13\frac{1}{3}\)

Mr. Verma can do a job in \(10\) days.

\(1\) day work of Mr. Verma \(= \frac{1}{10}\)

\(3\) days work of Mr. Verma \(= 3(\frac{1}{10}) = \frac{3}{10}\)

Amount of work left \(= 1- \frac{3}{10} = \frac{10-3}{10} = \frac{7}{10}\)

\(\frac{7}{10}\) Work is completed by Mr. Verma and helper together in \(4\) days.

\(1\) day work of Mr. Verma and helper together \(= (\frac{7}{10})(\frac{1}{4}) = \frac{7}{40}\)

Let the \(1\) day work of helper be \(= \frac{1}{x}\)

Mr. Verma can do a job in 10 days. A helper joins him after 3 days, an [#permalink]

Show Tags

12 Aug 2017, 23:58

If Mr. Verma can do the work in 10 days, after three days of working alone, Mr. Verma is joined by the helper and the helper complete the work in 4 days.

The helper does \(\frac{3}{10}\) of the total work in 4 days, which Mr. Verma would have done in the remaining 3 days had he worked alone on the work.

So, the helper does 3/10 of the work in 4 days and would do \(\frac{\frac{3}{10}}{4}\) or \(\frac{3}{40}\)th of the work in a day. Hence, it would take the helper \(\frac{1}{\frac{3}{40}}\) or \(13\frac{1}{3}\) to complete the work on his own(Option E)
_________________