It is currently 20 Nov 2017, 01:26

### 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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# a 30% solution of alcohol is mixed with a 50% solution of

 post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
Director
Joined: 12 Jun 2006
Posts: 531

Kudos [?]: 166 [0], given: 1

a 30% solution of alcohol is mixed with a 50% solution of [#permalink]

### Show Tags

20 Sep 2007, 05:27
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

a 30% solution of alcohol is mixed with a 50% solution of alcohol to form a 10 liter solution of 45% alchohol. How much of the 30% solution was used.

2.0 liters
2.5 liters
2.7 liters
3.0 liters
3.2 liters

__________________________________________________________

I'm doing this and coming up empty.
30(L)/100 + 50(10-L)/100 = (10)45/100

Kudos [?]: 166 [0], given: 1

Director
Joined: 11 Jun 2007
Posts: 909

Kudos [?]: 292 [0], given: 0

Re: what the %&*@ am i doing wrong? [Spoiler below red l [#permalink]

### Show Tags

20 Sep 2007, 05:41
ggarr wrote:
a 30% solution of alcohol is mixed with a 50% solution of alcohol to form a 10 liter solution of 45% alchohol. How much of the 30% solution was used.

2.0 liters
2.5 liters
2.7 liters
3.0 liters
3.2 liters

__________________________________________________________

I'm doing this and coming up empty.
30(L)/100 + 50(10-L)/100 = (10)45/100

It is actually quite simple. You want to find the ratio/weighted for each:

the answer should be B

dunno if I can explain this well.. there were these 'killer' notes that killersquirrel provided some time ago

30% + 50 % = 45% of a 10 liter solution
ratio of 30% : 50% ---> 1 : 3
so 30% = 1/4 or 25% of 10L solution = 2.5L

Kudos [?]: 292 [0], given: 0

Director
Joined: 12 Jun 2006
Posts: 531

Kudos [?]: 166 [0], given: 1

### Show Tags

20 Sep 2007, 05:50
beckee,

yeah. thanks. I have the notes. I'm just trying to solve the old fashioned way. i'd like to understand the traditional methods before moving on to the shortcuts

can anyone tell me what I'm doing wrong?
Quote:
a 30% solution of alcohol is mixed with a 50% solution of alcohol to form a 10 liter solution of 45% alchohol. How much of the 30% solution was used.

2.0 liters
2.5 liters
2.7 liters
3.0 liters
3.2 liters

__________________________________________________________

I'm doing this and coming up empty.
30(L)/100 + 50(10-L)/100 = (10)45/100

Kudos [?]: 166 [0], given: 1

Director
Joined: 11 Jun 2007
Posts: 909

Kudos [?]: 292 [0], given: 0

### Show Tags

20 Sep 2007, 05:56
ggarr wrote:
beckee,

yeah. thanks. I have the notes. I'm just trying to solve the old fashioned way. i'd like to understand the traditional methods before moving on to the shortcuts

can anyone tell me what I'm doing wrong?
Quote:
a 30% solution of alcohol is mixed with a 50% solution of alcohol to form a 10 liter solution of 45% alchohol. How much of the 30% solution was used.

2.0 liters
2.5 liters
2.7 liters
3.0 liters
3.2 liters

__________________________________________________________

I'm doing this and coming up empty.
30(L)/100 + 50(10-L)/100 = (10)45/100

I think you were getting there..but you have to set up simultaneous eqns. I would do it this way:

x + y = 10, or y = 10 - x

30x + 50 y = 45 (x + y)
30x + 50 (10-x) = 45 (10)
30x + 500 - 50x = 450
-20x = -50
20x = 50 -> 50/20
x = 2.5

see... still works out the old fashioned algebra way!

Kudos [?]: 292 [0], given: 0

Intern
Joined: 11 Sep 2007
Posts: 11

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

Re: what the %&*@ am i doing wrong? [Spoiler below red l [#permalink]

### Show Tags

20 Sep 2007, 12:11
beckee529 wrote:
ggarr wrote:
a 30% solution of alcohol is mixed with a 50% solution of alcohol to form a 10 liter solution of 45% alchohol. How much of the 30% solution was used.

2.0 liters
2.5 liters
2.7 liters
3.0 liters
3.2 liters

__________________________________________________________

I'm doing this and coming up empty.
30(L)/100 + 50(10-L)/100 = (10)45/100

It is actually quite simple. You want to find the ratio/weighted for each:

the answer should be B

dunno if I can explain this well.. there were these 'killer' notes that killersquirrel provided some time ago

30% + 50 % = 45% of a 10 liter solution
ratio of 30% : 50% ---> 1 : 3 so 30% = 1/4 or 25% of 10L solution = 2.5L

This intrigues me - I don't understand the ratio of 1:3. Can anyone provide a link to the killer notes? I'd like to learn this.

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

Manager
Joined: 17 May 2007
Posts: 72

Kudos [?]: 34 [0], given: 0

### Show Tags

20 Sep 2007, 12:20
someone had posted this file and i found it extremely helpful...took me all of 5 seconds to solve the problem
Attachments

File comment: mixture problems made easy
MixtureProblemsMadEasy.pdf [49.94 KiB]
Downloaded 79 times

 To download please login or register as a user

Kudos [?]: 34 [0], given: 0

CEO
Joined: 21 Jan 2007
Posts: 2734

Kudos [?]: 1076 [2], given: 4

Location: New York City

### Show Tags

17 Oct 2007, 12:35
2
This post received
KUDOS
beckee529 wrote:
ggarr wrote:
beckee,

yeah. thanks. I have the notes. I'm just trying to solve the old fashioned way. i'd like to understand the traditional methods before moving on to the shortcuts

can anyone tell me what I'm doing wrong?
Quote:
a 30% solution of alcohol is mixed with a 50% solution of alcohol to form a 10 liter solution of 45% alchohol. How much of the 30% solution was used.

2.0 liters
2.5 liters
2.7 liters
3.0 liters
3.2 liters

__________________________________________________________

I'm doing this and coming up empty.
30(L)/100 + 50(10-L)/100 = (10)45/100

I think you were getting there..but you have to set up simultaneous eqns. I would do it this way:

x + y = 10, or y = 10 - x

30x + 50 y = 45 (x + y)
30x + 50 (10-x) = 45 (10)
30x + 500 - 50x = 450
-20x = -50
20x = 50 -> 50/20
x = 2.5

see... still works out the old fashioned algebra way!

i like this way better. more intuitive

Kudos [?]: 1076 [2], given: 4

Director
Joined: 03 May 2007
Posts: 867

Kudos [?]: 271 [0], given: 7

Schools: University of Chicago, Wharton School
Re: what the %&*@ am i doing wrong? [Spoiler below red l [#permalink]

### Show Tags

17 Oct 2007, 17:04
ggarr wrote:
a 30% solution of alcohol is mixed with a 50% solution of alcohol to form a 10 liter solution of 45% alchohol. How much of the 30% solution was used.

2.0 liters
2.5 liters
2.7 liters
3.0 liters
3.2 liters

B. o.3x + 0.5 (1-x) = .45
x = 25%

so 30% alchohal has 25% of 10 lt = 2.5 lt.

Kudos [?]: 271 [0], given: 7

VP
Joined: 09 Jul 2007
Posts: 1098

Kudos [?]: 144 [0], given: 0

Location: London

### Show Tags

17 Oct 2007, 19:19
gowani wrote:
someone had posted this file and i found it extremely helpful...took me all of 5 seconds to solve the problem

Appreciate gowani,
it will take me now 3 seconds to solve this kinda PS!

Kudos [?]: 144 [0], given: 0

Non-Human User
Joined: 09 Sep 2013
Posts: 15639

Kudos [?]: 283 [0], given: 0

Re: a 30% solution of alcohol is mixed with a 50% solution of [#permalink]

### Show Tags

06 Apr 2017, 13:24
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

Kudos [?]: 283 [0], given: 0

Re: a 30% solution of alcohol is mixed with a 50% solution of   [#permalink] 06 Apr 2017, 13:24
Display posts from previous: Sort by

# a 30% solution of alcohol is mixed with a 50% solution of

 post reply Question banks Downloads My Bookmarks Reviews Important topics

Moderator: chetan2u

 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®.