It is currently 12 Dec 2017, 15:58

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.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

A can do 1/3 of the work in 5 days and B can do 2/5 of the work in 10

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

1 KUDOS received
Manager
Manager
User avatar
G
Joined: 07 Jul 2012
Posts: 219

Kudos [?]: 69 [1], given: 65

Location: India
Concentration: Finance
A can do 1/3 of the work in 5 days and B can do 2/5 of the work in 10 [#permalink]

Show Tags

New post 22 Oct 2017, 18:34
1
This post received
KUDOS
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

77% (01:09) correct 23% (01:22) wrong based on 56 sessions

HideShow timer Statistics

A can do \(\frac{1}{3}\) of the work in 5 days and B can do \(\frac{2}{5}\) of the work in 10 days. In how many days both A and B together can do the work?

A) 7\(\frac{3}{4}\)

B) 8\(\frac{4}{5}\)

C) 9\(\frac{3}{8}\)

D) 10

E) 12
[Reveal] Spoiler: OA

_________________

Kindly hit kudos if my post helps!

Kudos [?]: 69 [1], given: 65

1 KUDOS received
VP
VP
avatar
P
Joined: 22 May 2016
Posts: 1117

Kudos [?]: 397 [1], given: 640

A can do 1/3 of the work in 5 days and B can do 2/5 of the work in 10 [#permalink]

Show Tags

New post 22 Oct 2017, 23:10
1
This post received
KUDOS
varun4s wrote:
A can do \(\frac{1}{3}\) of the work in 5 days and B can do \(\frac{2}{5}\) of the work in 10 days. In how many days both A and B together can do the work?

A) 7\(\frac{3}{4}\)

B) 8\(\frac{4}{5}\)

C) 9\(\frac{3}{8}\)

D) 10

E) 12

This approach looks time-consuming. It isn't. Find and add rates. Work is 1; flip the rate to get the number of days it would take A and B, working together, to finish.

RATES: To find rates, use \(\frac{Work}{time} = rate\)

A's rate, in \(\frac{Work}{days}\):
\(\frac{(\frac{1}{3})}{5}=(\frac{1}{3} * \frac{1}{5})=\frac{1}{15}\)

B's rate:
\(\frac{(\frac{2}{5})}{10}=(\frac{2}{5} * \frac{1}{10})=\frac{2}{50}=\frac{1}{25}\)

Add rates of A, \(\frac{1}{15}\), and B, \(\frac{1}{25}\), with LCM of 150.
COMBINED RATE of A and B:

\((\frac{10}{150} + \frac{6}{150})=\frac{16}{150} = \frac{8}{75}\)

TIME: How many days does it take them, working together, to finish the job?
Job = 1
When work is 1, rate and time are inversely proportional.

Invert the combined rate, \(\frac{8}{75}\), to get the time: \(\frac{75}{8} = 9\frac{3}{8}\) days, OR

\(\frac{Work}{Rate} = time\)

\(\frac{1}{(\frac{8}{75})}= 1 * \frac{75}{8} =9\frac{3}{8}\)

Answer C

Kudos [?]: 397 [1], given: 640

Expert Post
Target Test Prep Representative
User avatar
S
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 1793

Kudos [?]: 980 [0], given: 5

Re: A can do 1/3 of the work in 5 days and B can do 2/5 of the work in 10 [#permalink]

Show Tags

New post 26 Oct 2017, 14:33
varun4s wrote:
A can do \(\frac{1}{3}\) of the work in 5 days and B can do \(\frac{2}{5}\) of the work in 10 days. In how many days both A and B together can do the work?

A) 7\(\frac{3}{4}\)

B) 8\(\frac{4}{5}\)

C) 9\(\frac{3}{8}\)

D) 10

E) 12


A’s rate is (1/3)/5 = 1/15 and B’s rate is (2/5)/10 = 2/50 = 1/25.

Their combined rate is 1/15 + 1/25 = 5/75 + 3/75 = 8/75.

Thus, the time it takes the two machines to complete the job is 1/(8/75) = 75/8 = 9 3/8 days.

Answer: C
_________________

Jeffery Miller
Head of GMAT Instruction

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

Kudos [?]: 980 [0], given: 5

Re: A can do 1/3 of the work in 5 days and B can do 2/5 of the work in 10   [#permalink] 26 Oct 2017, 14:33
Display posts from previous: Sort by

A can do 1/3 of the work in 5 days and B can do 2/5 of the work in 10

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.