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

 It is currently 28 Nov 2015, 01:31

### 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

# ration problem

 Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:
Manager
Status: GMAT Preperation
Joined: 04 Feb 2010
Posts: 103
Concentration: Social Entrepreneurship, Social Entrepreneurship
GPA: 3
WE: Consulting (Insurance)
Followers: 2

Kudos [?]: 71 [0], given: 15

ration problem [#permalink]  28 Sep 2010, 23:19
00:00

Difficulty:

35% (medium)

Question Stats:

78% (02:53) correct 22% (01:09) wrong based on 23 sessions
I am sure this will be easy for you guys.. but i had issues in understanding the explaination in OG, here goes the question:

qs 335 og10) the ratio, by volume, of soap to alcohol to water in a certain solution is 2.5.100. The solution will be altered so that the ratio of soap to alcohol is doubled while the ratio of soap to water is halfed. if the altered solution will contain 100 cubic cetimeters of alcohol, how many centemeters of water will it contain ?

50
200
400
625
800

I am getting 400
.. but the answer says 800 ?? can you explain what am i doing wrong here

S:A:W 2:50:100
new S:A 4:100
new S:W 1:100

if soap is if alcohol is 100 soap is 4 and water is 4*100= 400
[Reveal] Spoiler: OA
 Kaplan Promo Code Knewton GMAT Discount Codes Manhattan GMAT Discount Codes
Math Expert
Joined: 02 Sep 2009
Posts: 30377
Followers: 5091

Kudos [?]: 57356 [0], given: 8811

Re: ration problem [#permalink]  28 Sep 2010, 23:41
Expert's post
vanidhar wrote:
I am sure this will be easy for you guys.. but i had issues in understanding the explaination in OG, here goes the question:

qs 335 og10) the ratio, by volume, of soap to alcohol to water in a certain solution is 2.50.100. The solution will be altered so that the ratio of soap to alcohol is doubled while the ratio of soap to water is halfed. if the altered solution will contain 100 cubic cetimeters of alcohol, how many centemeters of water will it contain ?

50
200
400
625
800

I am getting 400
.. but the answer says 800 ?? can you explain what am i doing wrong here

S:A:W 2:50:100
new S:A 4:100
new S:W 1:100

if soap is if alcohol is 100 soap is 4 and water is 4*100= 400

Given: $$\frac{s}{{\frac{a}{w}}}=\frac{2}{{\frac{50}{100}}}$$;

The ratio of soap to alcohol is doubled --> $$\frac{s}{a}=2*\frac{2}{50}=\frac{4}{50}$$;

The ratio of soap to water is halved --> $$\frac{s}{w}=\frac{1}{2}*\frac{2}{100}=\frac{1}{100}=\frac{4}{400}$$;

New ratio: $$\frac{s}{{\frac{a}{w}}}=\frac{4}{{\frac{50}{400}}}$$ --> $$\frac{a}{w}=\frac{50}{400}$$ --> if $$a=2*50=100$$ then $$w=2*400=800$$.

Answer: E.
_________________
Intern
Joined: 19 Dec 2009
Posts: 33
Followers: 0

Kudos [?]: 26 [0], given: 9

600-700 ratios problem [#permalink]  18 Oct 2010, 10:23
The ratio by volume of soap to alcohol to water is 2:50:100. The solution will be altered so that the ratio of soap to alcohol is doubled while the ratio of soap to water is halved. If the altered solution will contain 100 cubic centimeters of alcohol, how many cubic centimeters of water will it contain?

a 50
b 200
c 400
d 625
e 800
Manager
Joined: 08 Sep 2010
Posts: 233
Location: India
WE 1: 6 Year, Telecom(GSM)
Followers: 4

Kudos [?]: 155 [0], given: 21

Re: 600-700 ratios problem [#permalink]  18 Oct 2010, 11:05
rtaha2412 wrote:
The ratio by volume of soap to alcohol to water is 2:50:100. The solution will be altered so that the ratio of soap to alcohol is doubled while the ratio of soap to water is halved. If the altered solution will contain 100 cubic centimeters of alcohol, how many cubic centimeters of water will it contain?

a 50
b 200
c 400
d 625
e 800

Ratio of S:A:W is 2:50:100

means S/A=2/50=1/25 and A/W= 50/100=1/2 Hence S/W = 1/50

Now in the altered solution S'/A'=(1/25)*2=2/25
While S'/W'=(1/50)*(1/2)=1/100
Hence A'/W'=(1/100)/(2/25)=1/8=25/(8*25) = 25/200

Therefore S':A':W'= 2:25:200

Now let the volume of new solution is x ml.

Alcohol Content ={25/(2+25+200)}*x =100
Hence x =(100*227)/25=908 ml

Hence the water content in new solution = {200/(2+25+200)}*908 = 800

Hence answer is E.

Consider KUDOS if it helped u in some way.
Senior Manager
Joined: 10 Nov 2010
Posts: 266
Location: India
Concentration: Strategy, Operations
GMAT 1: 520 Q42 V19
GMAT 2: 540 Q44 V21
WE: Information Technology (Computer Software)
Followers: 5

Kudos [?]: 155 [0], given: 22

water [#permalink]  20 Feb 2011, 07:29
Pls chk the image
Attachments

RP.JPG [ 28.03 KiB | Viewed 1459 times ]

_________________

The proof of understanding is the ability to explain it.

Manager
Joined: 14 Feb 2011
Posts: 196
Followers: 4

Kudos [?]: 87 [0], given: 3

Re: water [#permalink]  20 Feb 2011, 07:36
Initial ratio is S:A:W = 2:50:100
After changes, the ratio becomes 4:50:400 (as 2:50 is doubled so S becomes 4 units and 2:100 is halved, so new water units are 400 as new ratios need to be 2:200 or 4:400)
Now, If 50 corresponds to 100 cc, then 400 corresponds to 800 cc - Ans E
Math Forum Moderator
Joined: 20 Dec 2010
Posts: 2022
Followers: 145

Kudos [?]: 1297 [0], given: 376

Re: water [#permalink]  20 Feb 2011, 08:13
2:50:100

$$\frac{2}{50}$$ to be doubled $$\frac{2*2}{50} = \frac{4}{50}$$

$$\frac{2}{100}$$ is to be halved $$\frac{2}{2*100} = \frac{2}{200} = \frac{2*2}{200*2} = \frac{4}{400}$$

New proportion
Soap:Alcohol:Water
4:50:400

Alcohol is 100cc: Double of 50
Thus entire proportion should be multiplied by 2

8:100:800

Ans: "E"
_________________
Math Expert
Joined: 02 Sep 2009
Posts: 30377
Followers: 5091

Kudos [?]: 57356 [0], given: 8811

Re: water [#permalink]  20 Feb 2011, 09:14
Expert's post
Merging similar topics.
_________________
Re: water   [#permalink] 20 Feb 2011, 09:14
Similar topics Replies Last post
Similar
Topics:
1 Arithmetic operations on rational numbers problem 3 15 Aug 2011, 14:30
A math problem,s 2 07 Aug 2011, 04:02
ration proportion question 2 15 Mar 2010, 14:11
Rational Numbers 2 07 Feb 2010, 22:16
4 The number of stamps that Kaye and Alberto had were in the ration of 5 6 27 Sep 2009, 23:43
Display posts from previous: Sort by

# ration problem

 Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group and phpBB SEO 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®.