GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 23 Oct 2018, 22:56

Close

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

How many ounces of water must be added to 10 ounces of 3 % alcohol

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Manager
Manager
User avatar
G
Joined: 25 Sep 2018
Posts: 86
Location: United States (CA)
Concentration: Finance, Strategy
GMAT 1: 640 Q47 V30
GPA: 3.97
WE: Investment Banking (Investment Banking)
CAT Tests
How many ounces of water must be added to 10 ounces of 3 % alcohol  [#permalink]

Show Tags

New post 01 Oct 2018, 03:48
1
00:00
A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

79% (01:10) correct 21% (01:14) wrong based on 34 sessions

HideShow timer Statistics

How many ounces of water must be added to 10 ounces of 3 % alcohol and water solution to reduce the solution to 1 % alcohol.
A)5
B)10
C)15
D)20
E)30

_________________

Why do we fall?...So we can learn to pick ourselves up again



If you like the post, give it a KUDOS!

CEO
CEO
User avatar
P
Joined: 08 Jul 2010
Posts: 2585
Location: India
GMAT: INSIGHT
WE: Education (Education)
Reviews Badge
Re: How many ounces of water must be added to 10 ounces of 3 % alcohol  [#permalink]

Show Tags

New post 01 Oct 2018, 04:03
1
Abhi077 wrote:
How many ounces of water must be added to 10 ounces of 3 % alcohol and water solution to reduce the solution to 1 % alcohol.
A)5
B)10
C)15
D)20
E)30


Alchohol Quantity = (3/100)*10 = 0.3 Ounce

Now, After adding water the same alcohol quantity should represent 1% of the total new quantity

i.e. \(0.3 = (1/100)*(10+x)\) . where \(x\) is the quantity of water added

i.e. \(10+x = 30\)

i.e. \(x = 20\)

Answer: Option D
_________________

Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION

Intern
Intern
avatar
B
Joined: 21 Nov 2016
Posts: 37
CAT Tests
Re: How many ounces of water must be added to 10 ounces of 3 % alcohol  [#permalink]

Show Tags

New post 01 Oct 2018, 04:15
Let x be the no. of ounces of water to be added.
We know that 10 ounces of solution has 3% alcohol. That is 10*(3/100) = 0.3 ounces. So, 10 ounces of solution consists of 0.3 ounces of alcohol and 9.7 ounces of water.
Now, with the above information, since there is no addition of alcohol , the amount of alcohol in the resultant solution after addition of water will be the same 0.3 ounces. But, the percentage will change to 1%.
So, 0.3 = (10+x)(1/100)
Implies, 0.3 = 1/10 +x/100
0.3 = (10+x)/100
30 = 10 + x
x = 20.
So answer is 20 ounces.
CEO
CEO
User avatar
D
Joined: 12 Sep 2015
Posts: 3038
Location: Canada
Re: How many ounces of water must be added to 10 ounces of 3 % alcohol  [#permalink]

Show Tags

New post 03 Oct 2018, 10:52
Top Contributor
Abhi077 wrote:
How many ounces of water must be added to 10 ounces of 3 % alcohol and water solution to reduce the solution to 1 % alcohol.
A)5
B)10
C)15
D)20
E)30


The original solution contains 10 ounces
3% of that is alcohol
3% of 10 = 0.3
So, the original solution contains 0.3 ounces of alcohol

Let x = the amount of water (in ounces) that must be added
So, the volume of the RESULTING solution = 10 + x ounces

IMPORTANT: Since we're adding water only, the volume of alcohol does not change.
In other words, there are 0.3 ounces of alcohol in the RESULTING solution

We want the RESULTING solution to be 1% alcohol
In other words: (volume of alcohol in solution)/(total volume of solution) = 1/100
Rewrite as: 0.3 /(10 + x) = 1/100
Multiply both sides by (10 + x) to get: 0.3 = (10 + x)/100
Multiply both sides by 100 to get: 30 = 10 + x
Solve: x = 20

Answer: D

RELATED VIDEO FROM OUR COURSE

_________________

Brent Hanneson – GMATPrepNow.com
Image
Sign up for our free Question of the Day emails

GMATH Teacher
User avatar
S
Status: GMATH founder
Joined: 12 Oct 2010
Posts: 396
Re: How many ounces of water must be added to 10 ounces of 3 % alcohol  [#permalink]

Show Tags

New post 03 Oct 2018, 11:17
Abhi077 wrote:
How many ounces of water must be added to 10 ounces of 3 % alcohol and water solution to reduce the solution to 1 % alcohol.
A)5
B)10
C)15
D)20
E)30

Let´s do it with another technique: alligation!

Image

\(? = x\)

\({{10} \over {10 + x}} = {{1 - 0} \over {3 - 0}}\,\,\left( { = {{10} \over {30}}} \right)\,\,\,\,\,\,\, \Rightarrow \,\,\,\,\,? = 20\)


This solution follows the notations and rationale taught in the GMATH method.

Regards,
Fabio.
_________________

Fabio Skilnik :: https://www.GMATH.net (Math for the GMAT)
Course release PROMO : finish our test drive till 31/Oct with (at least) 60 correct answers out of 92 (12-questions Mock included) to gain a 60% discount!

GMAT Club Bot
Re: How many ounces of water must be added to 10 ounces of 3 % alcohol &nbs [#permalink] 03 Oct 2018, 11:17
Display posts from previous: Sort by

How many ounces of water must be added to 10 ounces of 3 % alcohol

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


cron
Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

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®.