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

 It is currently 18 Dec 2018, 09:21

### 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 December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
• ### Happy Christmas 20% Sale! Math Revolution All-In-One Products!

December 20, 2018

December 20, 2018

10:00 PM PST

11:00 PM PST

This is the most inexpensive and attractive price in the market. Get the course now!
• ### Key Strategies to Master GMAT SC

December 22, 2018

December 22, 2018

07:00 AM PST

09:00 AM PST

Attend this webinar to learn how to leverage Meaning and Logic to solve the most challenging Sentence Correction Questions.

# M31-02

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 51280

### Show Tags

07 Jun 2015, 07:29
00:00

Difficulty:

35% (medium)

Question Stats:

78% (01:10) correct 23% (01:39) wrong based on 40 sessions

### HideShow timer Statistics

By weight, liquid X makes up 0.8 percent of solution A and 1.8 percent of solution B. If 300 grams of solution A are mixed with 700 grams of solution B, then liquid X accounts for what percent of the weight of the resulting solution?

A. 1.5%
B. 1.9%
C. 10%
D. 15%
E. 19%

_________________
Math Expert
Joined: 02 Sep 2009
Posts: 51280

### Show Tags

07 Jun 2015, 07:29
Official Solution:

By weight, liquid X makes up 0.8 percent of solution A and 1.8 percent of solution B. If 300 grams of solution A are mixed with 700 grams of solution B, then liquid X accounts for what percent of the weight of the resulting solution?

A. 1.5%
B. 1.9%
C. 10%
D. 15%
E. 19%

Algebraic solution:

Liquid X makes up 0.8 percent of the weight of solution A and 1,8 percent of the weight of solution B. Therefore, 300 grams of solution A contain $$\frac{0.8}{100}*300 = 2.4$$ grams of liquid X, and 700 grams of solution B contain $$\frac{1.8}{100}*700 = 12.6$$ grams of liquid X. When the two solutions are mixed, the resulting solution weighs 1000 grams and contains $$2.4 + 12.6 = 15$$ grams of liquid X. This means that liquid X makes up $${15}{1000}*100 = 1.5%$$ of the weight of the resulting solution.

Shortcut solution:

Liquid X makes up 0.8 percent of solution A and 1.8 percent of solution B. The percent of liquid X in the resulting solution (A + B) must be between 0.8 percent and 1.8 percent. Only A fits.

_________________
Joined: 24 Oct 2012
Posts: 170

### Show Tags

07 Jun 2015, 23:22
Total volume of new solution = 300 + 700 = 1000 gms.

Liquid X in new solution = Liquid X from solution A + Liquid X from solution B
= 0.8 % 300 + 1.8 % 700 = 2.4 + 12.6 = 15 gms

percent of the weight of the resulting solution = 15 gms / 1000 = 1.5%

Option A

Note : Usually we commit mistake while considering the total volume, Here total volume is 1000 gms since it is addition of solution A (300 gms) and solution B ( 700 gms)
Manager
Joined: 26 Feb 2018
Posts: 79
Location: United Arab Emirates
GMAT 1: 710 Q47 V41
GMAT 2: 770 Q49 V47

### Show Tags

10 Mar 2018, 13:49
I think the answer choices tend too high to make this 700 level question. It is too easy to guess .... we have 300g of 0.8% and 700g - more than double the amount - of 1.8% so we immediately know two things without any calculation

1) new % will be between 0.8 and 1.8
2) new % will be closer to 1.8 than 0.8 as we have more of that solution - more than double in fact (weighted averages)

This means we can immediately bin answers B, C, D and E as they're all too high

I think an actual GMAT question would include some answer options lower than option A. Usually you can't eliminate 4 options so rapidly. GMAT answer selection usually includes some too high, some too low and one or two "trip up" answers
Manager
Joined: 26 Feb 2018
Posts: 53
Location: India
GMAT 1: 560 Q41 V27
WE: Web Development (Computer Software)

### Show Tags

19 Jun 2018, 13:36
I think this is a high-quality question and I agree with explanation.
Re M31-02 &nbs [#permalink] 19 Jun 2018, 13:36
Display posts from previous: Sort by

# M31-02

Moderators: chetan2u, Bunuel

 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®.