GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 21 Apr 2019, 13:22

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

Pipe A can fill a Tank in 18 Hours, Pipe B can empty a Tank in 12 Hour

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

Hide Tags

 
Intern
Intern
avatar
B
Joined: 26 Mar 2019
Posts: 12
Pipe A can fill a Tank in 18 Hours, Pipe B can empty a Tank in 12 Hour  [#permalink]

Show Tags

New post Updated on: 26 Mar 2019, 05:29
2
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

58% (02:15) correct 42% (03:10) wrong based on 31 sessions

HideShow timer Statistics

Pipe A can fill a Tank in 18 Hours, Pipe B can empty a Tank in 12 Hours, Pipe C can fill Tank in 6 Hours. The Tank is already filled up to 1/6 of its capacity. Now Pipe A is opened in the First Hour alone, Pipe B is opened in the Second Hour alone and Pipe C is opened in the Third Hour alone. This cycle is repeated until the Tank gets filled. Then in How many Hours does the rest of Tank gets filled?

A. 15 Hours
B. 18 Hours
C. 20 Hours
D. 24 Hours
E. None

Originally posted by Wasif007 on 26 Mar 2019, 05:26.
Last edited by Bunuel on 26 Mar 2019, 05:29, edited 2 times in total.
Renamed the topic, edited the question and added the OA.
Manager
Manager
User avatar
P
Status: Manager
Joined: 27 Oct 2018
Posts: 247
Location: Egypt
Concentration: Strategy, International Business
GPA: 3.67
WE: Pharmaceuticals (Health Care)
GMAT ToolKit User
Re: Pipe A can fill a Tank in 18 Hours, Pipe B can empty a Tank in 12 Hour  [#permalink]

Show Tags

New post 26 Mar 2019, 07:25
1
let the total work be 36 units (a common multiple for 18,12 & 6)
so per 1 hour, A would pump in 2 units, B would pump out 3 units & C would pump in 6 units
so 1 cycle of 3 hours would add 5 units in.

As \(\frac{1}{6}\) is already filled, so 6 units are already there.

at zero time: 6 units
after 3 hour (1 cycle): 6 + (2-3+6) = 6 + 5(1) = 11 , ... and so on .....

to fill the 36 units:
36 = 6 + 5x , where x is the number of cycles
x = 6, which represent 3 hours each, so 18 hours

so B
Attachments

Untitled.png
Untitled.png [ 2.5 KiB | Viewed 370 times ]


_________________
..Thanks for KUDOS
Image
Target Test Prep Representative
User avatar
P
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 5807
Location: United States (CA)
Re: Pipe A can fill a Tank in 18 Hours, Pipe B can empty a Tank in 12 Hour  [#permalink]

Show Tags

New post 27 Mar 2019, 19:08
Wasif007 wrote:
Pipe A can fill a Tank in 18 Hours, Pipe B can empty a Tank in 12 Hours, Pipe C can fill Tank in 6 Hours. The Tank is already filled up to 1/6 of its capacity. Now Pipe A is opened in the First Hour alone, Pipe B is opened in the Second Hour alone and Pipe C is opened in the Third Hour alone. This cycle is repeated until the Tank gets filled. Then in How many Hours does the rest of Tank gets filled?

A. 15 Hours
B. 18 Hours
C. 20 Hours
D. 24 Hours
E. None


We can see that for 3 consecutive hours, the tank is filled 1/18 - 1/12 + 1/6 = 2/36 - 3/36 + 6/36 = 5/36 of its capacity. Since 5/6 of the tank still needs to be filled and (5/6)/(5/36) = 6, we need 3 x 6 = 18 hours to fill the rest of the tank.

Answer: B
_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

GMAT Club Bot
Re: Pipe A can fill a Tank in 18 Hours, Pipe B can empty a Tank in 12 Hour   [#permalink] 27 Mar 2019, 19:08
Display posts from previous: Sort by

Pipe A can fill a Tank in 18 Hours, Pipe B can empty a Tank in 12 Hour

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


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| 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®.