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:

Eight litres are drawn off from a vessel full of water and s [#permalink]

Show Tags

12 Jun 2010, 14:17

5

This post received KUDOS

34

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

95% (hard)

Question Stats:

46% (03:56) correct
54% (02:54) wrong based on 531 sessions

HideShow timer Statistics

Eight litres are drawn off from a vessel full of water and substituted by pure milk. Again eight litres of the mixture are drawn off and substituted by pure milk. If the vessel now contains water and milk in the ratio 9:40, find the capacity of the vessel.

A. 21 liters B. 22 liters C. 20 liters D. 14 liters E. 28 liters

Re: Eight litres are drawn off from a vessel full of water and s [#permalink]

Show Tags

12 Jun 2010, 19:42

the equation you'd get once 8 lts are drawn the second time is: (w-16)/16 = 9/40 where w is the capacity of the vessel. Solving for w, w = 19.6. So, its C _________________

Please do consider giving kudos if you like my posts

Re: Eight litres are drawn off from a vessel full of water and s [#permalink]

Show Tags

12 Jun 2010, 22:37

iambroke wrote:

the equation you'd get once 8 lts are drawn the second time is: (w-16)/16 = 9/40 where w is the capacity of the vessel. Solving for w, w = 19.6. So, its C

Ya but second time 8 liters are removed from the mixture of milk and water not only water.

Eight litres are drawn off from a vessel full of water and substituted by pure milk. Again eight litres of the mixture are drawn off and substituted by pure milk.If the vessel now contains water and milk in the ratio 9:40, find the capacity of the vessel.

A. 21 liters B. 22 liters C. 20 liters D. 14 liters E. 28 liters

Let the capacity of the vessel be \(x\).

After the first removal there would be \(x-8\) liters of water left in the vessel. Note that the share of the water would be \(\frac{x-8}{x}\);

After the second removal, the removed mixture of 8 liters will contain \(8*\frac{x-8}{x}\) liters of water, so there will be \((x-8)-8*\frac{x-8}{x}=\frac{(x-8)^2}{x}\) liters of water left.

As the ratio of water to milk after that is \(\frac{9}{40}\), then the ratio of water to the capacity of the vessel would be \(\frac{9}{40+9}=\frac{9}{49}\).

So \(\frac{\frac{(x-8)^2}{x}}{x}=\frac{9}{49}\) --> \(\frac{(x-8)^2}{x^2}=\frac{9}{49}\) --> \(\frac{x-8}{x}=\frac{3}{7}\) --> \(x=14\).

Re: Eight litres are drawn off from a vessel full of water and s [#permalink]

Show Tags

13 Jun 2010, 22:39

After the second removal, the removed mixture of 8 liters will contain 8 * (x-8)/x liters of water, so there will be x-8-8 * (x-8)/8 = (x-8)^2/x liters of water left.

Re: Eight litres are drawn off from a vessel full of water and s [#permalink]

Show Tags

14 Jun 2010, 06:49

1

This post received KUDOS

bibha wrote:

After the second removal, the removed mixture of 8 liters will contain 8 * (x-8)/x liters of water, so there will be x-8-8 * (x-8)/8 = (x-8)^2/x liters of water left.

Please explain this part

Step1 :-

Water in vessel = x

8 liters is removed and replaced with milk

so now,

Water = x-8 Milk = 8

Step 2 :-

Now again 8 liters of mixture is removes , so water in that mixture is w = (x-8/x) * 8

So Total water removed = x-8-w = x-8-(x-8/x)*8 = (x^2-8x-8x-64)/x = (x^2-16x-64)/x

Re: Eight litres are drawn off from a vessel full of water and s [#permalink]

Show Tags

05 Sep 2010, 03:00

2

This post received KUDOS

virupaksh2010 wrote:

Eight litres are drawn off from a vessel full of water and substituted by pure milk. Again eight litres of the mixture are drawn off and substituted by pure milk.If the vessel now contains water and milk in the ratio 9:40, find the capacity of the vessel.

Possible AnswersSelected Possible Answer A. 21 litrers

B. 22 litres

C. 20 litres

D. 14 litres

E. 28 litres

Using Wine formula:

{ (P-8) / P }^2 = 9/49

P solves to 14 - Ans - D _________________

Consider giving Kudos if my post helps in some way

Bunuel, could you please pin point to a mistake in my reasoning?

Let T = total capacity of vessel

1.) the concentration of milk after the first round is 8/T 2.) After the second round the concentration of milk is \(40/49\)

\(8/T\) * (T-8) + 8 = \(40/49\) T

Now, I can't solve this equation. And even substituting answer choices won't help.

Where's the mistake?

Thank you very much.

Equation is correct.

\(\frac{8}{t}(t-8)+8=\frac{40}{49}t\) --> \(\frac{t-8}{t}+1=\frac{5t}{49}\). Now, if you substitute t=14 you'll see that it'll hold true. _________________

Re: Eight litres are drawn off from a vessel full of water and s [#permalink]

Show Tags

13 Feb 2012, 14:19

Bunuel, thanks a lot. I must have made some miscalculation.

Conceptually the question is interesting. However the numbers are quite "difficult" to work with. Do you think that a real GMAT question would have better numbers?

Bunuel, thanks a lot. I must have made some miscalculation.

Conceptually the question is interesting. However the numbers are quite "difficult" to work with. Do you think that a real GMAT question would have better numbers?

If you and up with an equation shown in my post above then it won't be that difficult to solve it, for your equation it's better to plug numbers of course. So I think that the question, though tough, is still a GMAT type. _________________

Bunuel, thanks a lot. I must have made some miscalculation.

Conceptually the question is interesting. However the numbers are quite "difficult" to work with. Do you think that a real GMAT question would have better numbers?

Actually, the numbers are quite suitable for a very efficient, quick and oral solution. This is what I thought of when I came up with the answer in 20 secs. Mind you, you need to go through the link provided below to understand this theory. Else the 20 sec solution will probably not make sense to you.

We are substituting milk so we should work with water.

Final concentration of water = 9/49 There were two iterations. So, 9/49 = (100%)*(Vi/Vf)^2 Vi/Vf = 3/7 Since we are putting 8 liters of water but difference between Vi and Vf is 4, final volume (which is also equal to volume of the vessel) must be twice too i.e. 7*2 = 14 liters.

Re: Eight litres are drawn off from a vessel full of water and s [#permalink]

Show Tags

31 Dec 2012, 12:01

1

This post was BOOKMARKED

nonameee wrote:

Bunuel, thanks a lot. I must have made some miscalculation.

Conceptually the question is interesting. However the numbers are quite "difficult" to work with. Do you think that a real GMAT question would have better numbers?

This is not a GMAT like question. Answers in gmat are usually sorted. as for as calculation is concerned it is easy. See below

Following formulae works in such scenario. More about its derivation later: If out of x, y is taken repeatedly after nth trial amount left is x(1-y/x)^n

Here asuming x ltr for water water left after two attempts is : x(1-8/x)^2

=> (x(1-8/x)^2)/x = 9/(9+40) => 1-8/x = 3/7 => 8/x = 4/7 or x = (7/4)*8 = 14ltr

Re: Eight litres are drawn off from a vessel full of water and s [#permalink]

Show Tags

25 May 2013, 11:28

Bunuel wrote:

virupaksh2010 wrote:

Eight litres are drawn off from a vessel full of water and substituted by pure milk. Again eight litres of the mixture are drawn off and substituted by pure milk.If the vessel now contains water and milk in the ratio 9:40, find the capacity of the vessel.

Possible AnswersSelected Possible Answer A. 21 litrers

B. 22 litres

C. 20 litres

D. 14 litres

E. 28 litres

Let the capacity of the vessel be \(x\).

After the first removal there would be \(x-8\) liters of water left in the vessel. Note that the share of the water would be \(\frac{x-8}{x}\);

After the second removal, the removed mixture of 8 liters will contain \(8*\frac{x-8}{x}\) liters of water, so there will be \(x-8-8*\frac{x-8}{x}=\frac{(x-8)^2}{x}\) liters of water left.

As the ratio of water to milk after that is \(\frac{9}{40}\), then the ratio of water to the capacity of the vessel would be \(\frac{9}{40+9}=\frac{9}{49}\).

So \(\frac{\frac{(x-8)^2}{x}}{x}=\frac{9}{49}\) --> \(\frac{(x-8)^2}{x^2}=\frac{9}{49}\) --> \(\frac{x-8}{x}=\frac{3}{7}\) --> \(x=14\).

Answer: D.

if we are removing 8 litres of mixture,does that mean we are removing water share ?? because in mixture,how can we remove water now,as it contains milk too now. why do we use 8*water share??Pls clarify..

Eight litres are drawn off from a vessel full of water and substituted by pure milk. Again eight litres of the mixture are drawn off and substituted by pure milk.If the vessel now contains water and milk in the ratio 9:40, find the capacity of the vessel.

Possible AnswersSelected Possible Answer A. 21 litrers

B. 22 litres

C. 20 litres

D. 14 litres

E. 28 litres

Let the capacity of the vessel be \(x\).

After the first removal there would be \(x-8\) liters of water left in the vessel. Note that the share of the water would be \(\frac{x-8}{x}\);

After the second removal, the removed mixture of 8 liters will contain \(8*\frac{x-8}{x}\) liters of water, so there will be \(x-8-8*\frac{x-8}{x}=\frac{(x-8)^2}{x}\) liters of water left.

As the ratio of water to milk after that is \(\frac{9}{40}\), then the ratio of water to the capacity of the vessel would be \(\frac{9}{40+9}=\frac{9}{49}\).

So \(\frac{\frac{(x-8)^2}{x}}{x}=\frac{9}{49}\) --> \(\frac{(x-8)^2}{x^2}=\frac{9}{49}\) --> \(\frac{x-8}{x}=\frac{3}{7}\) --> \(x=14\).

Answer: D.

if we are removing 8 litres of mixture,does that mean we are removing water share ?? because in mixture,how can we remove water now,as it contains milk too now. why do we use 8*water share??Pls clarify..

We are calculating how much water is left in the vessel after two removals. _________________

Re: Eight litres are drawn off from a vessel full of water and s [#permalink]

Show Tags

03 Jun 2013, 13:24

VeritasPrepKarishma wrote:

nonameee wrote:

Bunuel, thanks a lot. I must have made some miscalculation.

Conceptually the question is interesting. However the numbers are quite "difficult" to work with. Do you think that a real GMAT question would have better numbers?

Actually, the numbers are quite suitable for a very efficient, quick and oral solution. This is what I thought of when I came up with the answer in 20 secs. Mind you, you need to go through the link provided below to understand this theory. Else the 20 sec solution will probably not make sense to you.

We are substituting milk so we should work with water.

Final concentration of water = 9/49 There were two iterations. So, 9/49 = (100%)*(Vi/Vf)^2 Vi/Vf = 3/7 Since we are putting 8 liters of water but difference between Vi and Vf is 4, final volume (which is also equal to volume of the vessel) must be twice too i.e. 7*2 = 14 liters.

This is the kickoff for my 2016-2017 application season. After a summer of introspect and debate I have decided to relaunch my b-school application journey. Why would anyone want...

Check out this awesome article about Anderson on Poets Quants, http://poetsandquants.com/2015/01/02/uclas-anderson-school-morphs-into-a-friendly-tech-hub/ . Anderson is a great place! Sorry for the lack of updates recently. I...

Time is a weird concept. It can stretch for seemingly forever (like when you are watching the “Time to destination” clock mid-flight) and it can compress and...