BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Y is 30 percent liquid X

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
GMAT Instructor
Posts: 3650
Joined: Wed Jan 21, 2009 4:27 am
Location: India
Thanked: 267 times
Followed by:80 members
GMAT Score:760

Y is 30 percent liquid X

by sanju09 » Thu Jan 14, 2010 4:56 am
Solution Y is 30 percent liquid X and 70 percent water. If 2 kilograms of water evaporate from 8 kilograms of solution Y and 2 kilograms of solution Y are added to the remaining 6 kilograms of liquid, what percent of this new solution is liquid X?
(A) 27 ½%
(B) 30%
(C) 100/3%
(D) 37 ½%
(E) 40%
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com
Top
Source: — Problem Solving |
Junior | Next Rank: 30 Posts
Posts: 22
Joined: Fri Jan 08, 2010 7:46 am

by chrsrook » Thu Jan 14, 2010 7:42 am
Given: Y= 0.3X+0.7W

In 8Kgs of Y, there are 8*0.3=2.4 Kgs of X and 8*0.7=5.6 Kgs of water.

When 2Kgs of water evaporate, there are 3.6Kgs of water left along with the original 2.4Kgs of X.

Now, 2Kgs of Y are added to the existing 6Kgs of Y.

The 2 Kgs of Y will also contain X and W in the same ration (0.3 and 0.7).

So X in 2Kgs of Y= 2*0.3=0.6 and W in 2 Kgs of Y=2*0.7=1.4

Total Y= 6+2=8
Total X= 2.4+0.6= 3
Total W=3.6+1.4= 5

% of X in Y= 3/8*100= 37.5%

Thanks
Top
Master | Next Rank: 500 Posts
Posts: 107
Joined: Sat Feb 27, 2010 11:10 am
GMAT Score:690

by singhsa » Sun Sep 12, 2010 4:31 am
The solution seems manageable. I was wondering if there is a way of solving this using Allegation Method.
Top
Newbie | Next Rank: 10 Posts
Posts: 4
Joined: Sun Apr 25, 2010 6:37 am
Thanked: 1 times

by gmatt14 » Fri Oct 15, 2010 7:42 am
Most importantly, we have to concentrate on what is being asked! If you concentrate solely on X, you can solve this question fast.

Consider the attached table, which helped me out a lot to grasp this concept.

From the table we gain the equation:

0.3 (8) + 0.3 (2) = 0.3 (8+2) = 0.3 (10) = 3

8 kg of solution Y contains 3 kg of solution X:

3/8 = 37.5 %

Hope this helps! ;-)
Attachments
Mixture.xls
(19.5 KiB) Downloaded 133 times
Top
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Fri Oct 15, 2010 8:30 am
sanju09 wrote:Solution Y is 30 percent liquid X and 70 percent water. If 2 kilograms of water evaporate from 8 kilograms of solution Y and 2 kilograms of solution Y are added to the remaining 6 kilograms of liquid, what percent of this new solution is liquid X?
(A) 27 ½%
(B) 30%
(C) 100/3%
(D) 37 ½%
(E) 40%
The water that is being replaced is 2/8 = 25% of the total solution. We are replacing this 25% with solution Y. Thus, the percentage of liquid X in the total solution is going to increase by 25%:

1.25*30 = 37.5.

The correct answer is D.

Similarly, if the water being replaced were 4/8 = 50% of the total solution, the percentage of liquid X in the total solution would increase by 50%. The resulting solution would be 1.5*30 = 45% X and 55% water.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
Post new topic Post Reply
• Page 1 of 1