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

Redeem

solution X and Y

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 71
Joined: Sun May 18, 2008 11:04 pm
Thanked: 1 times

solution X and Y

by charmaine » Thu Sep 11, 2008 5:52 pm
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?

answer: 37 1/2%

thanks for the help :)
Top
Source: — Problem Solving |
Junior | Next Rank: 30 Posts
Posts: 11
Joined: Sun Jun 29, 2008 8:11 pm

by superbrat123 » Thu Sep 11, 2008 8:16 pm
In 8 kilogram solution of Y
x=30% of 8 = 2.4, water = 70% of 8 = 5.6
Now, 2 kilogram of water is evaporated => 5.6-2.0 = 3.6

In 2 kilogram solution of Y, x=30%of2 = 0.6, water = 70%of2=1.4

In the final solution, we have
x = 2.4+0.6, total water = 3.6+1.4

x as percent of x+water = 3.0/3.0+5.0 = 3/8 = 37.5%
Top
Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pm
Thanked: 331 times
Followed by:11 members

by cramya » Fri Sep 19, 2008 7:07 pm
Convert the kilograms to grams (1kg = 1000g) Since we are asked percent it doesnt change. Even if the question was what kg of x is present in the final solution its an easy divide by 1000

It may be easy to work with in 2 minutes. Just my opinion!! Good luck!
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 7:36 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 139 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 12:28 pm
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 would increase by 50% in the resulting solution. 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