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M11-11

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M11-11  [#permalink]

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New post 15 Sep 2014, 23:44
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Difficulty:

  35% (medium)

Question Stats:

79% (01:26) correct 21% (01:55) wrong based on 90 sessions

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Tub A and tub B contain 540 liters of water each. Every minute tub A loses 25 liters of water while tub B loses 15 liters. If in \(X\) minutes tub B will contain 6 times as much water as tub A, what is \(X\)?

A. 15
B. 20
C. 25
D. 30
E. 40

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Re M11-11  [#permalink]

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New post 15 Sep 2014, 23:44
2
Official Solution:

Tub A and tub B contain 540 liters of water each. Every minute tub A loses 25 liters of water while tub B loses 15 liters. If in \(X\) minutes tub B will contain 6 times as much water as tub A, what is \(X\)?

A. 15
B. 20
C. 25
D. 30
E. 40

The equation is \(6(540 - 25X) = 540 - 15X\) from where \(X = 20\).

Answer: B
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Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


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Re: M11-11  [#permalink]

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New post 30 Jan 2015, 12:54
Bunuel wrote:
Official Solution:

Tub A and tub B contain 540 liters of water each. Every minute tub A loses 25 liters of water while tub B loses 15 liters. If in \(X\) minutes tub B will contain 6 times as much water as tub A, what is \(X\)?

A. 15
B. 20
C. 25
D. 30
E. 40

The equation is \(6(540 - 25X) = 540 - 15X\) from where \(X = 20\).

Answer: B

Hi,
I find it hard to visualize this problem. I am following MGMAT approach of creating the table. Can you please explain a bit more for this problem?
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Posts: 50585
Re: M11-11  [#permalink]

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New post 31 Jan 2015, 05:10
1
pairakesh10 wrote:
Bunuel wrote:
Official Solution:

Tub A and tub B contain 540 liters of water each. Every minute tub A loses 25 liters of water while tub B loses 15 liters. If in \(X\) minutes tub B will contain 6 times as much water as tub A, what is \(X\)?

A. 15
B. 20
C. 25
D. 30
E. 40

The equation is \(6(540 - 25X) = 540 - 15X\) from where \(X = 20\).

Answer: B

Hi,
I find it hard to visualize this problem. I am following MGMAT approach of creating the table. Can you please explain a bit more for this problem?


Every minute tub A, containing 540 liters of water, loses 25 liters of water, thus after x minutes it'll contain 540 - 25x liters of water.

Every minute tub B, containing 540 liters of water, loses 15 liters of water, thus after x minutes it'll contain 540 - 15x liters of water.

We are told that after x minutes tub B will contain 6 times as much water as tub A, thus 6(540 - 25x) = 540 - 15x.

Hope it's clear.
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Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


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Re: M11-11  [#permalink]

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New post 12 Sep 2017, 15:01
Thanks Bunuel! Excellent question. I'd like to further refine my solving on these types of problems - could you suggest some other examples/problems that will help me?
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Re: M11-11  [#permalink]

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New post 12 Sep 2017, 20:03
vpustovoyt wrote:
Thanks Bunuel! Excellent question. I'd like to further refine my solving on these types of problems - could you suggest some other examples/problems that will help me?


17. Work/Rate Problems



For more check:
ALL YOU NEED FOR QUANT ! ! !
Ultimate GMAT Quantitative Megathread

Hope it helps.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


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M11-11  [#permalink]

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New post 12 Mar 2018, 01:45
Hi Bunuel,

How can I deploy the table method to answer this question?

I tried and failed to use it.

Rate * Time = Work
A: 25litres/min (under rate column) 540 litres (under work column)
B: 15 litres/min (under rate column) 540 litres (under work column)
B: X (under time column) 6A (under work column)

Can you please show me how you can answer the question using this method?

I ask because it's best to be consistent with a particular approach to most questions...and I can't for the life of me understand how you know how the X is inserted...when I tried your method I didn't know where to put the X so I did 540-15L = 6(540) - 25(6)L

Why for instance is it 25X and 15X respectively as opposed to 25/X and 15/x respectively? Especially since it's per minute - meaning divided by minutes.

Thanks.

Tosin
GMAT Club Bot
M11-11 &nbs [#permalink] 12 Mar 2018, 01:45
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