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

 It is currently 22 Oct 2019, 04:53

### 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

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

# A mixture of oil, water, and vinegar contains 10% oil. After all of th

Author Message
TAGS:

### Hide Tags

Senior Manager
Joined: 12 Aug 2015
Posts: 280
Concentration: General Management, Operations
GMAT 1: 640 Q40 V37
GMAT 2: 650 Q43 V36
GMAT 3: 600 Q47 V27
GPA: 3.3
WE: Management Consulting (Consulting)
A mixture of oil, water, and vinegar contains 10% oil. After all of th  [#permalink]

### Show Tags

23 Aug 2015, 12:55
4
9
00:00

Difficulty:

25% (medium)

Question Stats:

72% (01:20) correct 28% (01:36) wrong based on 622 sessions

### HideShow timer Statistics

A mixture of oil, water, and vinegar contains 10% oil. After all of the water evaporates, what percent of the mixture is oil?

(1) Before the water evaporated, the mixture exactly filled a one liter bottle.

(2) Before the water evaporated, vinegar accounted for forty percent of the mixture.

_________________
KUDO me plenty
CEO
Joined: 20 Mar 2014
Posts: 2595
Concentration: Finance, Strategy
Schools: Kellogg '18 (M)
GMAT 1: 750 Q49 V44
GPA: 3.7
WE: Engineering (Aerospace and Defense)
Re: A mixture of oil, water, and vinegar contains 10% oil. After all of th  [#permalink]

### Show Tags

23 Aug 2015, 17:48
5
1
A mixture of oil, water, and vinegar contains 10% oil. After all of the water evaporates, what percent of the mixture is oil?

(1) Before the water evaporated, the mixture exactly filled a one liter bottle.

(2) Before the water evaporated, vinegar accounted for forty percent of the mixture.

Let L,V and W stand for proportions of oil, vinegar and water in the mixture. Given, L/T = 0.1 ---> L = 0.1T. % of L when all water evaporates ---> w=0 --> L/(L+V) = ?

Per statement 1, T=1 liter. Does not provide any information about the proportion of vinegar in the mixture. Not sufficient.

Per statement 2, V = 0.4T ----> ratio : L/(L+0.4T) and from L=0.1T ---> ratio = 0.1T/(0.1T+0.4T) ---> thus you get a sufficient answer. B is sufficient to answer.

##### General Discussion
GMATH Teacher
Status: GMATH founder
Joined: 12 Oct 2010
Posts: 935
Re: A mixture of oil, water, and vinegar contains 10% oil. After all of th  [#permalink]

### Show Tags

16 Sep 2018, 18:19
2
1
A mixture of oil, water, and vinegar contains 10% oil. After all of the water evaporates, what percent of the mixture is oil?

(1) Before the water evaporated, the mixture exactly filled a one liter bottle.

(2) Before the water evaporated, vinegar accounted for forty percent of the mixture.

$${\text{Before: x}}\,\,{\text{liters}}\,\,\,\,\left\{ \begin{gathered} {\text{oil}}\,\,:0.1x\,\,{\text{liters}} \hfill \\ water\,\,:\,\,k\left( {0.9x} \right)\,\,{\text{liters}} \hfill \\ vinegar\,\,:\,\,\,\left( {1 - k} \right)\left( {0.9x} \right)\,\,{\text{liters}}\,\, \hfill \\ \end{gathered} \right.\,\,\,\,\,\,\,\left( {0 < k < 1} \right)$$

$${\text{After}}:\,\,\,{\text{x}}\left( {1 - 0.9k} \right)\,\,\,{\text{liters}}\,\,\,\left\{ \begin{gathered} {\text{oil}}\,\,:0.1x\,\,{\text{liters}} \hfill \\ water\,\,:\,\,0\,\,{\text{liters}} \hfill \\ vinegar\,\,:\,\,\,\left( {1 - k} \right)\left( {0.9x} \right)\,\,{\text{liters}}\,\, \hfill \\ \end{gathered} \right.$$

$$? = \frac{{0.1x}}{{x\left( {1 - 0.9k} \right)}} = \frac{{0.1}}{{1 - 0.9k}}\,\,\,\,\, \Leftrightarrow \,\,\,\,\,\boxed{? = k}\,$$

$$\left( 1 \right)\,\,\,x = 1\,\,\,\left\{ \begin{gathered} \,{\text{Take}}\,\,\,k = 0.1 \hfill \\ \,{\text{Take}}\,\,\,k = 0.2 \hfill \\ \end{gathered} \right.\,\,\,\,\,\, \Rightarrow \,\,\,\,\,{\text{INSUFF}}.$$

$$\left( 2 \right)\,\,\,\,\,\frac{{\left( {1 - k} \right)\left( {0.9x} \right)\,\,}}{x} = \frac{2}{5}\,\,\,\,\, \Rightarrow \,\,\,\,k\,\,{\text{unique}}\,\,\,\,\, \Rightarrow \,\,\,\,{\text{SUFF}}.\,$$

This solution follows the notations and rationale taught in the GMATH method.

Regards,
Fabio.
_________________
Fabio Skilnik :: GMATH method creator (Math for the GMAT)
Our high-level "quant" preparation starts here: https://gmath.net
Manager
Joined: 01 Jan 2018
Posts: 80
Re: A mixture of oil, water, and vinegar contains 10% oil. After all of th  [#permalink]

### Show Tags

02 Oct 2018, 05:33
Since the mixture contains oil, water, and vinegar of which 10% is oil. So, 90% is water+vinegar.
When water evaporates only water+vinegar remains.
From stat 1 we cannot conclude the volume of vinegar hence not suff.
In stat 2 we are given % of vinegar. So we can say that since water=50% ,vinegar=40% and oil=10%
when water evaporates we can calculate % of oil.Hence B is correct choice.
_________________
+1 Kudos if you find this post helpful
Manager
Joined: 16 Jul 2018
Posts: 60
Re: A mixture of oil, water, and vinegar contains 10% oil. After all of th  [#permalink]

### Show Tags

09 Jan 2019, 11:33

Hey gladi could you please shed some light on my issue on this one?
My query is that do the proportions remain the same after water evaporation? I mean beforehand vinegar accounted for 40% of the mixture and oil 10% but after the water is evaporated will it still account for 40% ?

For instance lets say a mixture which is consisted of a, b and c liquids a=5 b=4 c=5 at first b accounts for 40% of the mixture a+b+c but when c is removed b accounts for 80% of the mixture.
Senior PS Moderator
Status: It always seems impossible until it's done.
Joined: 16 Sep 2016
Posts: 737
GMAT 1: 740 Q50 V40
GMAT 2: 770 Q51 V42
Re: A mixture of oil, water, and vinegar contains 10% oil. After all of th  [#permalink]

### Show Tags

09 Jan 2019, 11:48
1
Hi there UNSTOPPABLE12,

To answer your question - No. Think of it like this - Statement B says that Vinegar is 40% while oil is 10%.. so water will be the remaining or 50% of the mixture.

Assuming that only water evaporates - only vinegar and oil will remain...
So now vinegar will be 40% out of 50% total or Vinegar will be 80% of the new mixture whereas oil will be 20%. Their relative percentages double as the mixture becomes half of original

Hope it is clear.

UNSTOPPABLE12 wrote:

Hey gladi could you please shed some light on my issue on this one?
My query is that do the proportions remain the same after water evaporation? I mean beforehand vinegar accounted for 40% of the mixture and oil 10% butafter the water is evaporated will it still account for 40% ?

For instance lets say a mixture which is consisted of a, b and c liquids a=5 b=4 c=5 at first b accounts for 40% of the mixture a+b+c but when c is removed b accounts for 80% of the mixture.

_________________
Regards,

“Do. Or do not. There is no try.” - Yoda (The Empire Strikes Back)
Manager
Joined: 16 Jul 2018
Posts: 60
Re: A mixture of oil, water, and vinegar contains 10% oil. After all of th  [#permalink]

### Show Tags

09 Jan 2019, 12:26
Hi there UNSTOPPABLE12,

To answer your question - No. Think of it like this - Statement B says that Vinegar is 40% while oil is 10%.. so water will be the remaining or 50% of the mixture.

Assuming that only water evaporates - only vinegar and oil will remain...
So now vinegar will be 40% out of 50% total or Vinegar will be 80% of the new mixture whereas oil will be 20%. Their relative percentages double as the mixture becomes half of original

Hope it is clear.

UNSTOPPABLE12 wrote:

Hey gladi could you please shed some light on my issue on this one?
My query is that do the proportions remain the same after water evaporation? I mean beforehand vinegar accounted for 40% of the mixture and oil 10% butafter the water is evaporated will it still account for 40% ?

For instance lets say a mixture which is consisted of a, b and c liquids a=5 b=4 c=5 at first b accounts for 40% of the mixture a+b+c but when c is removed b accounts for 80% of the mixture.

Thanks gladi brilliant remarks as usual.
Re: A mixture of oil, water, and vinegar contains 10% oil. After all of th   [#permalink] 09 Jan 2019, 12:26
Display posts from previous: Sort by