Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 31 Aug 2016, 23:33

### 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

# Events & Promotions

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

# Two important formulas for mixture problems

Author Message
TAGS:

### Hide Tags

Intern
Joined: 11 Aug 2009
Posts: 10
Followers: 1

Kudos [?]: 29 [5] , given: 3

Two important formulas for mixture problems [#permalink]

### Show Tags

19 Aug 2009, 06:10
5
KUDOS
3
This post was
BOOKMARKED
I came across two methods which I found very handy in solving some types of mixture problems. So I thought of sharing it with the gc community.
here they are

Rule of Alligation
It is the rule that enables us to find the ratio in which two or more ingredients at the given price must be mixed to produce a mixture of a desired price.

Mean Price: The cost price of a unit quantity of the mixture is called mean price.

Rule of Alligation

If two quantities are mixed, then

$$\frac{Quantity of cheaper}{Quantity of dearer}=\frac{(C.P.) of dearer - (Mean Price)}{(Mean Price) - (C.P.)}$$

Taking a simple example

In what ratio must rice at 9.30 /kg be mixed with rice at 10.80/kg so that the mixture be worth 10/kg?

C.P of cheaper=9.30
C.P of dearer=10.80
C.P of mean or mean price = 10.0

so putting the values in the formula
$$\frac{Qc}{Qd}=\frac{Cd-Cm}{Cm-Cc}$$

=$$\frac{10.80-10}{10-9.3}$$

=8:7 Ans
_________________

WHEN HAMMER IS THE ONLY TOOL U HAVE..EVERY PROBLEM SHOULD SEEM LIKE A PIN....

Last edited by joebloggs on 19 Aug 2009, 06:52, edited 2 times in total.
Intern
Joined: 11 Aug 2009
Posts: 10
Followers: 1

Kudos [?]: 29 [2] , given: 3

### Show Tags

19 Aug 2009, 06:25
2
KUDOS
5
This post was
BOOKMARKED
Suppose a container contains x units of liquid from which y units are taken out and replaced with water.

After n operations, the quantity of pure liquid = $$[x(1-\frac{y}{x})^n]$$

Example: A container contains 40 liters of milk. From this container 4 litres of milk was taken and replaced by water. This process was repeated further two times. How much milk is now contained by the container?

Amount of milk left after 3 operations = $$[40(1-\frac{4}{40})^3]liters = (40 *\frac{9}{10}^3)$$ = 29.16 liters
_________________

WHEN HAMMER IS THE ONLY TOOL U HAVE..EVERY PROBLEM SHOULD SEEM LIKE A PIN....

Intern
Joined: 11 Aug 2009
Posts: 10
Followers: 1

Kudos [?]: 29 [1] , given: 3

Re: Two important formulas for mixture problems [#permalink]

### Show Tags

19 Aug 2009, 06:37
1
KUDOS
you also might wanna see a short method for mixture problems used by Economist
check out this problem

http://gmatclub.com/forum/how-much-of-the-mixture-is-to-be-removed-and-replaced-82423.html

Hope this post helps

Soon I'll be posting some mixture problems which I couldn't solve in one go ...

see ya ....
_________________

WHEN HAMMER IS THE ONLY TOOL U HAVE..EVERY PROBLEM SHOULD SEEM LIKE A PIN....

Current Student
Joined: 18 Jun 2009
Posts: 358
Location: San Francisco
Followers: 10

Kudos [?]: 73 [0], given: 15

Re: Two important formulas for mixture problems [#permalink]

### Show Tags

19 Aug 2009, 12:40
nice post .. thanks .. +1
Manager
Joined: 16 Apr 2009
Posts: 243
Schools: Ross
Followers: 2

Kudos [?]: 74 [0], given: 10

Re: Two important formulas for mixture problems [#permalink]

### Show Tags

19 Aug 2009, 12:53
Keep up the good work !
_________________

Keep trying no matter how hard it seems, it will get easier.

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 11191
Followers: 512

Kudos [?]: 134 [0], given: 0

Re: Two important formulas for mixture problems [#permalink]

### Show Tags

19 Oct 2013, 07:03
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.
_________________
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 11191
Followers: 512

Kudos [?]: 134 [0], given: 0

Re: Two important formulas for mixture problems [#permalink]

### Show Tags

03 Nov 2014, 18:59
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.
_________________
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 11191
Followers: 512

Kudos [?]: 134 [0], given: 0

Re: Two important formulas for mixture problems [#permalink]

### Show Tags

01 May 2016, 02:19
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.
_________________
Re: Two important formulas for mixture problems   [#permalink] 01 May 2016, 02:19
Similar topics Replies Last post
Similar
Topics:
1 Mixture Problem 4 19 Nov 2011, 19:18
MIXTURE PROBLEM! 0 25 Oct 2011, 18:06
1 Mixture Problem 6 24 Oct 2011, 09:54
1 Mixture Problem 5 24 Oct 2011, 09:42
MIXTURE PROBLEM 4 26 Apr 2011, 07:26
Display posts from previous: Sort by