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

It is currently 20 Jun 2018, 23:36

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Two alloys A and B are composed of two basic elements. The

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

Hide Tags

2 KUDOS received
Manager
Manager
avatar
Joined: 15 Apr 2012
Posts: 92
Location: Bangladesh
Concentration: Technology, Entrepreneurship
GMAT 1: 460 Q38 V17
GPA: 3.56
Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post Updated on: 04 May 2017, 22:19
2
32
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

60% (02:13) correct 40% (02:12) wrong based on 655 sessions

HideShow timer Statistics

Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ?

(A) 1 : 1
(B) 2 : 3
(C) 5 : 2
(D) 4 : 3
(E) 7 : 9



Edit: Source -> NOVA.

Originally posted by farukqmul on 30 Jun 2012, 21:15.
Last edited by stonecold on 04 May 2017, 22:19, edited 1 time in total.
Added the Source.
4 KUDOS received
Current Student
User avatar
B
Joined: 29 Mar 2012
Posts: 317
Location: India
GMAT 1: 640 Q50 V26
GMAT 2: 660 Q50 V28
GMAT 3: 730 Q50 V38
GMAT ToolKit User
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 01 Jul 2012, 01:33
4
1
farukqmul wrote:
Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two
basic elements in the two alloys are 5 : 3 and 1 : 2, respectively. A new alloy X is formed by mixing
the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements
in alloy X ?

(A) 1 : 1
(B) 2 : 3
(C) 5 : 2
(D) 4 : 3
(E) 7 : 9

Hi,

Proportion of 1st element in A = 5/8
Proportion of 1st element in B = 1/3
let, the proportion of 1st element in mixture = x
using allegations:
Attachment:
all.jpg
all.jpg [ 7.83 KiB | Viewed 28861 times ]

\(\frac {x-1/3}{5/8-x}= \frac 43\)
on solving, x=0.5
thus, proportion of two elements in the mixture is 1:1

Answer (A)

Regards,
Expert Post
4 KUDOS received
Veritas Prep GMAT Instructor
User avatar
P
Joined: 16 Oct 2010
Posts: 8102
Location: Pune, India
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 15 Aug 2012, 05:36
4
10
farukqmul wrote:
Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ?

(A) 1 : 1
(B) 2 : 3
(C) 5 : 2
(D) 4 : 3
(E) 7 : 9


Responding to a pm:

When you need to find the average, it is better to use the formula in its original form: Avg = (C1*w1 + C2*w2)/(w1 + w2)
Avg = [(5/8)*4 + (1/3)*3]/(4+3) = 1/2
Ratio of the 2 elements in the mixture = 1:1


Obviously the formula will work in the other form too though it is best to use that when you need to find the ratio of the weights. Using the formula in the other form: w1/w2 = (A2 - Aavg)/(Aavg - A1)
element 1 in A = 5/8
element 1 in B = 1/3
element 1 in mixture = x

4/3 = (1/3 - x) / (x - 5/8)
4/3(x - 5/8) = 1/3 - x
(7/3)x = 7/6
x = 1/2
(You made a calculation error)

Ratio of elements in the mixture = 1:1
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for $199

Veritas Prep Reviews

5 KUDOS received
Director
Director
User avatar
Joined: 22 Mar 2011
Posts: 605
WE: Science (Education)
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 15 Aug 2012, 06:00
5
2
farukqmul wrote:
Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ?

(A) 1 : 1
(B) 2 : 3
(C) 5 : 2
(D) 4 : 3
(E) 7 : 9


Mixture A has a total of 5 + 3 = 8 parts. If in the final mixture this represents 4 parts, then the total number of parts in mixture B should be (8/4)*3 = 6.
So, we should take of mixture B a quantity with 2 and 4 parts, respectively.

This will give us in the final mixture (5 + 2) : (3 + 4), which means 7:7, or 1:1.

Answer A.
_________________

PhD in Applied Mathematics
Love GMAT Quant questions and running.

3 KUDOS received
Intern
Intern
avatar
Joined: 19 Feb 2012
Posts: 21
Location: India
Concentration: Technology, General Management
Schools: WBS '15
GMAT 1: 700 Q48 V38
GPA: 3.36
WE: Analyst (Computer Software)
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 29 Oct 2012, 02:48
3
Alloy A:
Since F:S = 5:3, and 5+3=8, F/total = 5/8.

Alloy B:
Since F:S = 1:2, and 1+2 = 3, F/total = 1/3.

Mixture T:
A:B = 4:3.
If we mix 8 units of A with 6 units of B, we get:
Amount of F in alloy A = (5/8)8 = 5 units
Amount of F in alloy B = (1/3)6 = 2 units.
(Total F)/(Mixture T) = (5+2)/(8+6) = 7/14 = 1/2.
Since 1/2 of the mixture is composed of F, F:S = 1:1.
4 KUDOS received
Intern
Intern
avatar
Joined: 31 Oct 2012
Posts: 22
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 15 Dec 2012, 22:30
4
2
Ratio of Elements
A - 5:3 / 5x:3x
B - 1:2 / 1y:2y

Ratio of Alloys
A+B - 4:3
ie. A:B = 4:3
(5x+3x):(1y+2y) = 4:3
8x:3y = 4:3
x:y = 1:2 => y = 2x

Ratio of elements in (A+B)
1st element in A and B / 2nd Element in A and B
(5x + y)/(3x + 2y) but y = 2x
ie. 7x/7x = 1:1
Ans A
Intern
Intern
User avatar
Joined: 24 Apr 2012
Posts: 48
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 16 Dec 2012, 04:01
let the two elements be 1 and 2,element 1 in alloy A =5/8 , element 1 in alloy B=1/3, element 1 in mixture=x, therefore 4/3=(1/3-x)/(5/8-x)= ½ so the answer is (A).
_________________

www.mnemoniceducation.com

TURN ON YOUR MINDS!!!

VP
VP
User avatar
Status: Been a long time guys...
Joined: 03 Feb 2011
Posts: 1271
Location: United States (NY)
Concentration: Finance, Marketing
GPA: 3.75
GMAT ToolKit User Premium Member
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 16 Dec 2012, 04:07
1
Another approach to this problem is by weighted average.

In such problems , it becomes easier if we stick to one metal only. So the compostion of first metal in A is 5/8 and and in B is 1/3.
So when we combine A and B, the compostion will be between 5/8 and 1/3.

Now in the diagram attached:
The "distance" between the compositions of first metal in A and B is 7/24.
The composition of the final mixture is given as 4:3 i.e. A's 4 parts and B's 3 parts. But when we interpret in the distance format, the sequence flips i.e. the distance between final mixture and A will be 3 units and that of between final mixture and B will be 4 units.

Now to calculate the compostion of the first metal in X, add the 4 units to 1/3.
i.e. \(4/7 *\)\(7/24\) \(+1/3\) OR
subtract 3 units from 5/8
i.e. \(5/8 -\) \(4/7\)\(* 7/24\).
This will come out as 50%.
Therefore the other metal will also constitute 50%.
Hence the ratio is 1:1.
+1A
Attachments

solution.png
solution.png [ 13.08 KiB | Viewed 27181 times ]


_________________

Prepositional Phrases Clarified|Elimination of BEING| Absolute Phrases Clarified
Rules For Posting
www.Univ-Scholarships.com

Intern
Intern
avatar
Joined: 05 Sep 2011
Posts: 7
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 10 Apr 2013, 21:19
VeritasPrepKarishma wrote:
farukqmul wrote:
Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ?

(A) 1 : 1
(B) 2 : 3
(C) 5 : 2
(D) 4 : 3
(E) 7 : 9


Responding to a pm:

When you need to find the average, it is better to use the formula in its original form: Avg = (C1*w1 + C2*w2)/(w1 + w2)
Avg = [(5/8)*4 + (1/3)*3]/(4+3) = 1/2
Ratio of the 2 elements in the mixture = 1:1


Obviously the formula will work in the other form too though it is best to use that when you need to find the ratio of the weights. Using the formula in the other form: w1/w2 = (A2 - Aavg)/(Aavg - A1)
element 1 in A = 5/8
element 1 in B = 1/3
element 1 in mixture = x

4/3 = (1/3 - x) / (x - 5/8)
4/3(x - 5/8) = 1/3 - x
(7/3)x = 7/6
x = 1/2
(You made a calculation error)

Ratio of elements in the mixture = 1:1



Dear karishma

thanks a lot. that's a great solution but one point is subtle to me. would you please explain which part of the question indicates that we should go with weighted average formula?
thanks again in advance.
Regards

Posted from my mobile device
Expert Post
Veritas Prep GMAT Instructor
User avatar
P
Joined: 16 Oct 2010
Posts: 8102
Location: Pune, India
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 11 Apr 2013, 07:15
marzan2011 wrote:


Dear karishma

thanks a lot. that's a great solution but one point is subtle to me. would you please explain which part of the question indicates that we should go with weighted average formula?
thanks again in advance.
Regards

Posted from my mobile device


It's a matter of practice. You will never be given 'find the weighted average'. When you have two things (classes, groups, mixtures, solutions) and they talk about the total, average or something, that should give you a hint that weighted average might work here.
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for $199

Veritas Prep Reviews

Manager
Manager
avatar
B
Joined: 07 May 2015
Posts: 93
GMAT ToolKit User
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 04 Aug 2015, 18:29
VeritasPrepKarishma wrote:
farukqmul wrote:
Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ?

(A) 1 : 1
(B) 2 : 3
(C) 5 : 2
(D) 4 : 3
(E) 7 : 9


Responding to a pm:

When you need to find the average, it is better to use the formula in its original form: Avg = (C1*w1 + C2*w2)/(w1 + w2)
Avg = [(5/8)*4 + (1/3)*3]/(4+3) = 1/2
Ratio of the 2 elements in the mixture = 1:1


Obviously the formula will work in the other form too though it is best to use that when you need to find the ratio of the weights. Using the formula in the other form: w1/w2 = (A2 - Aavg)/(Aavg - A1)
element 1 in A = 5/8
element 1 in B = 1/3
element 1 in mixture = x

4/3 = (1/3 - x) / (x - 5/8)
4/3(x - 5/8) = 1/3 - x
(7/3)x = 7/6
x = 1/2
(You made a calculation error)

Ratio of elements in the mixture = 1:1


Hi,

Thanks alot for the great solution, just one quick question, if we are getting the x (which is the amount of A in mixture) = 1/2, then how are we getting to ratio as 1:1?
Is it because 1/2 stands for A/A+B so 1/1+1 and hence A and B are in ration 1:1

Thanks in advance!
Expert Post
Veritas Prep GMAT Instructor
User avatar
P
Joined: 16 Oct 2010
Posts: 8102
Location: Pune, India
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 04 Aug 2015, 21:39
neeraj609 wrote:
VeritasPrepKarishma wrote:
farukqmul wrote:
Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ?

(A) 1 : 1
(B) 2 : 3
(C) 5 : 2
(D) 4 : 3
(E) 7 : 9


Responding to a pm:

When you need to find the average, it is better to use the formula in its original form: Avg = (C1*w1 + C2*w2)/(w1 + w2)
Avg = [(5/8)*4 + (1/3)*3]/(4+3) = 1/2
Ratio of the 2 elements in the mixture = 1:1


Obviously the formula will work in the other form too though it is best to use that when you need to find the ratio of the weights. Using the formula in the other form: w1/w2 = (A2 - Aavg)/(Aavg - A1)
element 1 in A = 5/8
element 1 in B = 1/3
element 1 in mixture = x

4/3 = (1/3 - x) / (x - 5/8)
4/3(x - 5/8) = 1/3 - x
(7/3)x = 7/6
x = 1/2
(You made a calculation error)

Ratio of elements in the mixture = 1:1


Hi,

Thanks alot for the great solution, just one quick question, if we are getting the x (which is the amount of A in mixture) = 1/2, then how are we getting to ratio as 1:1?
Is it because 1/2 stands for A/A+B so 1/1+1 and hence A and B are in ration 1:1

Thanks in advance!


Yes, element 1 in mixture is element 1 in total.
So element 1 is 1 part out of 2 total parts. The other part must be the other basic element.
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for $199

Veritas Prep Reviews

VP
VP
avatar
G
Joined: 07 Dec 2014
Posts: 1018
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 29 Sep 2015, 13:37
let E=element 1
4(5/8)+3(1/3)=7E
E=1/2
ratio between elements=1:1
Expert Post
2 KUDOS received
Veritas Prep GMAT Instructor
User avatar
P
Joined: 16 Oct 2010
Posts: 8102
Location: Pune, India
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 12 Oct 2016, 04:10
2
VeritasPrepKarishma wrote:
farukqmul wrote:
Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ?

(A) 1 : 1
(B) 2 : 3
(C) 5 : 2
(D) 4 : 3
(E) 7 : 9


Responding to a pm:

When you need to find the average, it is better to use the formula in its original form: Avg = (C1*w1 + C2*w2)/(w1 + w2)
Avg = [(5/8)*4 + (1/3)*3]/(4+3) = 1/2
Ratio of the 2 elements in the mixture = 1:1


Obviously the formula will work in the other form too though it is best to use that when you need to find the ratio of the weights. Using the formula in the other form: w1/w2 = (A2 - Aavg)/(Aavg - A1)
element 1 in A = 5/8
element 1 in B = 1/3
element 1 in mixture = x

4/3 = (1/3 - x) / (x - 5/8)
4/3(x - 5/8) = 1/3 - x
(7/3)x = 7/6
x = 1/2
(You made a calculation error)

Ratio of elements in the mixture = 1:1


Responding to a pm:

Quote:
I don't completely understand your solution. Why did you do Avg = [(5/8)*4 + (1/3)*3]/(4+3) rather than Avg = [(5/8)*4 + (1/3)*4]/(4+3)? The 1/3 also refers to the first part of the ratio doesn't it?


The formula is

\(Cavg = \frac{(C1*w1 + C2*w2)}{(w1 + w2)}\)

The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 (first element is 5/8 of Total) and 1 : 2 (first element is 1/3 of Total)

"A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3" - This implies that w1:w2 = 4:3

\(Cavg = \frac{(5/8)*4 + (1/3)*3}{4 + 3}\)
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for $199

Veritas Prep Reviews

1 KUDOS received
BSchool Forum Moderator
User avatar
D
Joined: 12 Aug 2015
Posts: 2642
GRE 1: 323 Q169 V154
GMAT ToolKit User Premium Member
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 04 May 2017, 22:30
1
Tremendous Question.
Here is what i did on this one -->

The ratio of two alloys is 4/3

Let A be 4x and B be 3x.

For A --> 5k+3k=4x => k=x/2

Element 1-> 2.5x
Element 2->1.5x

For B --> p+2p=3x => p=x

Element 1->x
Element 2->2x

Hence in the combination -->
Element 1 ->3.5x
Element 2->3.5x
Ratio => 1:1

SMASH THAT A.

_________________


MBA Financing:- INDIAN PUBLIC BANKS vs PRODIGY FINANCE!

Getting into HOLLYWOOD with an MBA!

The MOST AFFORDABLE MBA programs!

STONECOLD's BRUTAL Mock Tests for GMAT-Quant(700+)

AVERAGE GRE Scores At The Top Business Schools!

Manager
Manager
User avatar
S
Joined: 14 Sep 2016
Posts: 60
Concentration: Finance, Economics
Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 05 May 2017, 08:30
farukqmul wrote:
Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ?

(A) 1 : 1
(B) 2 : 3
(C) 5 : 2
(D) 4 : 3
(E) 7 : 9



Edit: Source -> NOVA.



Alloy A
5:3 or \(\frac{5}{8}\) of Element 1

Alloy B
1:2 or \(\frac{1}{3}\) of Element 1

Alloy X
4:3 or \(\frac{4}{7}\) of Alloy A and \(\frac{3}{7}\) of Alloy B

Amount of Element 1 in both Alloys (A + B)
\(\frac{4}{7}\) of the mixture will be \(\frac{5}{8}\) Element 1 + the remaining \(\frac{3}{7}\) of the mixture will be \(\frac{1}{3}\) of Element 1

Math
\(\frac{4}{7}\) X \(\frac{5}{8}\) + \(\frac{3}{7}\) X \(\frac{1}{3}\) = \(\frac{28}{56}\) is Element 1 = a 1:1 ratio
Expert Post
1 KUDOS received
Veritas Prep GMAT Instructor
User avatar
P
Joined: 16 Oct 2010
Posts: 8102
Location: Pune, India
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 26 May 2017, 19:45
1
VeritasPrepKarishma wrote:
farukqmul wrote:
Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ?

(A) 1 : 1
(B) 2 : 3
(C) 5 : 2
(D) 4 : 3
(E) 7 : 9


Responding to a pm:

When you need to find the average, it is better to use the formula in its original form: Avg = (C1*w1 + C2*w2)/(w1 + w2)
Avg = [(5/8)*4 + (1/3)*3]/(4+3) = 1/2
Ratio of the 2 elements in the mixture = 1:1


Obviously the formula will work in the other form too though it is best to use that when you need to find the ratio of the weights. Using the formula in the other form: w1/w2 = (A2 - Aavg)/(Aavg - A1)
element 1 in A = 5/8
element 1 in B = 1/3
element 1 in mixture = x

4/3 = (1/3 - x) / (x - 5/8)
4/3(x - 5/8) = 1/3 - x
(7/3)x = 7/6
x = 1/2
(You made a calculation error)

Ratio of elements in the mixture = 1:1

Responding to a pm:

Quote:
I am trying to understand the approach to the solution you posted to the Alloy-composition question above (I know it is quite a while ago..).
I understand how you get to the equation [5/8*4+1/3*3]/3+4 since 4 parts of the new mix need to contain 5/8 of element 1 from alloy A (correct? :) ) and the solution 1/2 but I don't understand what the 1/2 actually represent and how you the get to a ratio of 1:1.
Could you please help me and explain the reasoning?

I unfortunately also do not understand how you get to the equation 4/3 = (1/3 - x) / (x - 5/8) (ie. Why do you subtract x from 1/3 to represent alloy a? :shock: )


We have a standard weighted average formula:
Avg = (C1*w1 + C2*w2)/(w1 + w2)
We can rearrange the terms in this formula to give us:
w1/w2 = (A2 - Aavg)/(Aavg - A1)

Both are the same formula. A is the quantity that you need to average. w1 and w2 are the weights in which this quantity is mixed.

We are given the following:
The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 and 1 : 2, respectively.
So we can say that the concentration of the first element is 5/(5+3) = 5/8 of alloy A and the concentration of the first element in alloy B is 1/(1+2) = 1/3 of alloy B.
We need to find the average concentration Aavg.

A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3.
The two allows are mixed in the ratio 4:3. So w1/w2 = 4/3

For more, check:
https://www.veritasprep.com/blog/2011/0 ... -averages/
https://www.veritasprep.com/blog/2011/0 ... -mixtures/
https://www.veritasprep.com/blog/2014/1 ... -averages/
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for $199

Veritas Prep Reviews

Expert Post
Director
Director
User avatar
B
Joined: 17 Dec 2012
Posts: 635
Location: India
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 09 Jun 2017, 16:33
farukqmul wrote:
Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ?

(A) 1 : 1
(B) 2 : 3
(C) 5 : 2
(D) 4 : 3
(E) 7 : 9
Edit: Source -> NOVA.

1. Let the quantity of A and B be 4x and 3x

2. (Quantity of Alloy A *Proportion of element 1 + Quantity of Alloy B * proportion of element 1) / ( Quantity of Alloy A *Proportion of element 2 + Quantity of Alloy B * proportion of element 2) = Quantity of element 1 in mixture / Quantity of element 2 in mixture

3. 4x *(5/8) + 3x*(1/3) / 4x*(3/8) + 3x*(2/3) = 1/1
_________________

Srinivasan Vaidyaraman
Sravna
http://www.sravnatestprep.com/best-online-gre-preparation.php

Improve Intuition and Your Score
Systematic Approaches

Manager
Manager
avatar
B
Joined: 28 Jan 2017
Posts: 58
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 25 Jun 2017, 03:15
farukqmul wrote:
Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ?

(A) 1 : 1
(B) 2 : 3
(C) 5 : 2
(D) 4 : 3
(E) 7 : 9



Edit: Source -> NOVA.


Hi

I am getting the below answer (23/18). Can someone explain me where I am making the mistake.
Attachments

File comment: Calculation
Math_problem.jpg
Math_problem.jpg [ 75.31 KiB | Viewed 2736 times ]

Manager
Manager
avatar
B
Joined: 28 Jan 2017
Posts: 58
Re: Two alloys A and B are composed of two basic elements. The [#permalink]

Show Tags

New post 25 Jun 2017, 05:18
CantDropThisTime wrote:
farukqmul wrote:
Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ?

(A) 1 : 1
(B) 2 : 3
(C) 5 : 2
(D) 4 : 3
(E) 7 : 9



Edit: Source -> NOVA.


Hi

I am getting the below answer (23/18). Can someone explain me where I am making the mistake.


I understood where did I make the mistake :) :)
Re: Two alloys A and B are composed of two basic elements. The   [#permalink] 25 Jun 2017, 05:18

Go to page    1   2    Next  [ 23 posts ] 

Display posts from previous: Sort by

Two alloys A and B are composed of two basic elements. The

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


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®.