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

It is currently 14 Oct 2019, 08:38

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

Material A costs $3 per kilogram, and Material B costs $5 per kilogram

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

Hide Tags

Find Similar Topics 
Intern
Intern
avatar
Joined: 09 Feb 2011
Posts: 9
Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post Updated on: 05 Aug 2017, 00:16
9
131
00:00
A
B
C
D
E

Difficulty:

  85% (hard)

Question Stats:

55% (02:07) correct 45% (02:37) wrong based on 2670 sessions

HideShow timer Statistics

Material A costs $3 per kilogram, and Material B costs $5 per kilogram. If 10 kilograms of Material K consists of x kilograms of Material A and y kilograms of Material B, is x > y ?

(1) y > 4
(2) The cost of the 10 kilograms of Material K is less than $40.

Originally posted by alltimeacheiver on 11 Feb 2011, 02:26.
Last edited by Bunuel on 05 Aug 2017, 00:16, edited 3 times in total.
Edited the question and added the OA.
Most Helpful Expert Reply
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58316
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 11 Feb 2011, 03:50
24
31
alltimeacheiver wrote:
Material A costs $3 per kilogram, and material B costs $5 per kilogram. If 10 kilograms of material K consists of x kilograms of material A and y kilograms of material B, is x >y?

(1) y > 4
(2) The cost of the 10 kilograms of material K is less than $40


Material A costs $3 per kilogram, and material B costs $5 per kilogram. If 10 kilograms of material K consists of x kilograms of material A and y kilograms of material B, is x >y?

Given: x+y=10. Question: is x>y?

(1) y > 4. Clearly insufficient: if y=4.5<x=5.5 the answer will be YES but if y=6>x=4 the answer will be NO.

(2) The cost of the 10 kilograms of material K is less than $40 ---> 3x+5y<40, as y=10-x then: 3x+5(10-x)<40 --> 2x>10 --> x>5, so x>y. Sufficient.

Answer: B.
_________________
Most Helpful Community Reply
Manager
Manager
User avatar
Status: Employed
Joined: 17 Nov 2011
Posts: 78
Location: Pakistan
Concentration: International Business, Marketing
GMAT 1: 720 Q49 V40
GPA: 3.2
WE: Business Development (Internet and New Media)
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 16 Feb 2012, 08:47
8
The answer has to be B.

Let's setup the weighted average equation for this question:

\(x\) kilograms at 3$ per Kilogram
\(y\) kilograms at 5$ per Kilogram
Yields \(10\) kilograms at z$ per Kilogram
We also know that \(x+y=10\)
So Equation would be : \(3(x)+5(y)=10(z)\)

Now let's look at the statements:

Statement 1: \(y>4\)

Remember: \(x+y=10\)
So: \(x\) could range between 0 and 6. Insufficient

Statement 2: Cost is \(<40\)

So \(3(x)+5(y)<40\)
But \(x+y=10\) so \(x=10-y\)
So \(3(10-y)+5(y)<40\)
So \(30-2y+5y<40\)
So \(2y<10\)
So \(y<5\)

If \(y<5\) then \(x>5\) so \(x>y\) Sufficient

Hence B
_________________
"Nowadays, people know the price of everything, and the value of nothing." Oscar Wilde
General Discussion
Intern
Intern
User avatar
Joined: 21 Feb 2011
Posts: 1
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 10 Mar 2011, 05:42
5
Material A cost 3$/kg and B cost 5$/kg.
If 10 kg of material K consist of x kg of A and y kg of B, is x>y?

1- y>4

2- the cost of 10kg of K is less than $40.

Solution: -

1) Insufficient
Material A cost 3$/kg and B cost 5$/kg
x+y=10 and y>4 is all we have from statement 1. Since the total price is not fixed, (x,y) can be anything satisfying x+y=10 ....even (5,5) can't be wrong in this case

2) Sufficient
Material A cost 3$/kg and B cost 5$/kg
x+y=10 and the cost of 10kg of K is less than $40.
Therefore, 3x+5y<40 => 3x+(10-x)5<40 => 10<2x => 5<x
So, x>5 and x+y=10 means x>y

Hope it helps !!!
_________________
Set out each day believing in your dreams.
Know without a doubt that you were made for amazing things.
Director
Director
avatar
Status: Impossible is not a fact. It's an opinion. It's a dare. Impossible is nothing.
Affiliations: University of Chicago Booth School of Business
Joined: 03 Feb 2011
Posts: 655
Reviews Badge
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 10 Mar 2011, 07:22
3
x = 10 - y
Rephrasing the question - Is x > y?
or Is 10 - y > y
Is y < 5 ?

1. Insufficient
2. Sufficient
3x + 5y < 40
3(10 - y) + 4y < 40
2y < 10
Hence y < 5

Hence B.
alltimeacheiver wrote:
Material A costs $3 per kilogram, and material B costs $5 per kilogram. If 10 kilograms
of material K consists of x kilograms of material A and y kilograms of material B, is x >
y?
(1) y > 4
(2) The cost of the 10 kilograms of material K is less than $40
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58316
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 13 Jun 2013, 02:15
2
3
Director
Director
User avatar
Joined: 25 Apr 2012
Posts: 661
Location: India
GPA: 3.21
WE: Business Development (Other)
Reviews Badge
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 15 Jun 2013, 14:13
2
alltimeacheiver wrote:
Material A costs $3 per kilogram, and Material B costs $5 per kilogram. If 10 kilograms of Material K consists of x kilograms of Material A and y kilograms of Material B, is x > y ?

(1) y > 4
(2) The cost of the 10 kilograms of Material K is less than $40.



Material K cost "C" can be found out by calculating

C= (3*x+5*y)/10

Now the cost C will be close to Material A cost if x is more than y and vice versa

from St 1 we have y>4
For eg y=5, x=5 Cost of Material K will be $4/kg (in between price of Material A and Material B)
now if x=4,y=6 ,Cost of material K will be be $ 4.2/kg
if x=1,y=9 then Cost of material will be 4.8$ per kg
but if we take y=4 and x=6 we get cost of material K as $ 3.8 per kg less than $ 4 which would have been the price had both material A and B were added equally.

Therefore if x>y we should have price of Material K < $ 4kg

Hence St1 alone not sufficient as we can have x=y or x<y

St 2, The cost of the 10 kilograms of Material K is less than $40.[/quote]

Cost of Material per kg <$4 which meets our above requirement which means x>y

Therefore ans st B
_________________

“If you can't fly then run, if you can't run then walk, if you can't walk then crawl, but whatever you do you have to keep moving forward.”
Manager
Manager
avatar
S
Joined: 26 Jan 2015
Posts: 91
CAT Tests
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 28 Nov 2015, 04:50
Bunuel wrote:
alltimeacheiver wrote:
Material A costs $3 per kilogram, and material B costs $5 per kilogram. If 10 kilograms of material K consists of x kilograms of material A and y kilograms of material B, is x >y?

(1) y > 4
(2) The cost of the 10 kilograms of material K is less than $40


Material A costs $3 per kilogram, and material B costs $5 per kilogram. If 10 kilograms of material K consists of x kilograms of material A and y kilograms of material B, is x >y?

Given: x+y=10. Question: is x>y?

(1) y > 4. Clearly insufficient: if y=4.5<x=5.5 the answer will be YES but if y=6>x=4 the answer will be NO.

(2) The cost of the 10 kilograms of material K is less than $40 ---> 3x+5y<40, as y=10-x then: 3x+5(10-x)<40 --> 2x>10 --> x>5, so x>y. Sufficient.

Answer: B.


Hi...If in the question it is mentioned that x and y are integers, then will the answer be D? because it will lead to contradiction that 'x is not greater than y' or will still answer be b because (there is no clarity whether x may be equal to y or may be less than y'?
_________________
Kudos is the best way to say Thank you! Please give me a kudos if you like my post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58316
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 28 Nov 2015, 07:59
2
Alok322 wrote:
Bunuel wrote:
alltimeacheiver wrote:
Material A costs $3 per kilogram, and material B costs $5 per kilogram. If 10 kilograms of material K consists of x kilograms of material A and y kilograms of material B, is x >y?

(1) y > 4
(2) The cost of the 10 kilograms of material K is less than $40


Material A costs $3 per kilogram, and material B costs $5 per kilogram. If 10 kilograms of material K consists of x kilograms of material A and y kilograms of material B, is x >y?

Given: x+y=10. Question: is x>y?

(1) y > 4. Clearly insufficient: if y=4.5<x=5.5 the answer will be YES but if y=6>x=4 the answer will be NO.

(2) The cost of the 10 kilograms of material K is less than $40 ---> 3x+5y<40, as y=10-x then: 3x+5(10-x)<40 --> 2x>10 --> x>5, so x>y. Sufficient.

Answer: B.


Hi...If in the question it is mentioned that x and y are integers, then will the answer be D? because it will lead to contradiction that 'x is not greater than y' or will still answer be b because (there is no clarity whether x may be equal to y or may be less than y'?


If we were told that x and y are integers then y > 4 (5, 6, 7, ...) together with x + y = 10, would be sufficient to say that x is NOT greater than y. But in this case the question would be flawed because the statements would contradict each other which never happens in proper GMAT DS questions.

Hope it's clear.
_________________
Intern
Intern
avatar
Joined: 02 Oct 2014
Posts: 8
Reviews Badge
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 23 Dec 2015, 07:42
1
Thank you Buennel!

Very important point since i came here with the same problem and i pulled my hair over this for a solid 20 minutes.

If you simplify (2) it results in y < 5. While (1) says that y > 4.

Contradicting? No. We might think its contradictory if we assume that the qty involved are integers (common mistake, since qty usually are).

Do note that the question does not say that x or y are integers. And it is for this reason, otherwise, the question would logically be incorrect.

My takeaway:
1) Always remember that GMAT statements are never contradictory
2) If at some point, it seems like they are contradicting, it could mean
a) i've done it incorrectly
b) they aren't contradicting in the first place! :p
3) In such WP questions, ask yourself, are the quantities divisible into decimals?
Veritas Prep GMAT Instructor
User avatar
V
Joined: 16 Oct 2010
Posts: 9699
Location: Pune, India
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 16 Mar 2016, 07:35
1
alltimeacheiver wrote:
Material A costs $3 per kilogram, and Material B costs $5 per kilogram. If 10 kilograms of Material K consists of x kilograms of Material A and y kilograms of Material B, is x > y ?

(1) y > 4
(2) The cost of the 10 kilograms of Material K is less than $40.


Responding to a pm:

Quote:
In solving the B part of this question (like in many situation i have faced) 3[5]+5[5]=15+25="40<40"
This is my question:
[Q-1] Can we ever take 40<40 ie x<x when x is same number. Similarly x>x and so on in GMAT?



To be honest, I am not sure what your question means.
40 < 40 is not correct and neither is x < x since both are equal.
And no, x > x doesn't work either.
If they are the same number, one cannot be greater than the other. You might want to show me the steps of where you come across this problem.
_________________
Karishma
Veritas Prep GMAT Instructor

Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >
Intern
Intern
avatar
Joined: 29 Mar 2017
Posts: 2
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 05 Apr 2017, 10:35
I have a question,

the question provide 10=x+y, it's about the weight

but it doesn't mean 3x+5y<40 (money), cuz 40=10k, we don't know the unit price of k, so i don't think it's right.

Is there anything wrong of me? I was confused a litte...hehe
Retired Moderator
avatar
V
Joined: 22 Jun 2014
Posts: 1093
Location: India
Concentration: General Management, Technology
GMAT 1: 540 Q45 V20
GPA: 2.49
WE: Information Technology (Computer Software)
GMAT ToolKit User
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 05 Apr 2017, 11:34
1
dxhzhu wrote:
I have a question,

the question provide 10=x+y, it's about the weight

but it doesn't mean 3x+5y<40 (money), cuz 40=10k, we don't know the unit price of k, so i don't think it's right.

Is there anything wrong of me? I was confused a litte...hehe


x + y = 10 ---equation (1)

from stmt-2 we can say 3x + 5y < 40

multiply equation (1) by 3 and you get 3x + 3y = 30

3x + 5y < 40 (to subtract the below equation, consider < as = sign)
3x + 3y = 30

2y < 10 (isnt it? because if you subtract 30 from somthing less than 40 then you get something less than 10)

hence y < 5, it means x > y because x + y = 10

so B is correct. Hope your doubt is clear.
_________________
Senior Manager
Senior Manager
User avatar
G
Joined: 19 Oct 2012
Posts: 260
Location: India
Concentration: General Management, Operations
GMAT 1: 660 Q47 V35
GMAT 2: 710 Q50 V38
GPA: 3.81
WE: Information Technology (Computer Software)
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 29 Aug 2017, 12:13
alltimeacheiver wrote:
Material A costs $3 per kilogram, and Material B costs $5 per kilogram. If 10 kilograms of Material K consists of x kilograms of Material A and y kilograms of Material B, is x > y ?

(1) y > 4
(2) The cost of the 10 kilograms of Material K is less than $40.


The question can solved using weighted average concept easily without pen and paper calculation i.e can be solved within 30 seconds.

10kg of mixture uses x kg of Material A and y kg of Material B. If both X and Y are equal, the cost of the 10kg of material K will be right in the middle of $30 and $50 i.e. at $40.

But using stmt B, 10kg of K costs less than $40 dollars i.e. the cost shift towards $30. Hence clearly the quantity of X is more and Y. Hence B is sufficient.

I hope that helps.
_________________
Citius, Altius, Fortius
Intern
Intern
avatar
S
Joined: 11 Sep 2017
Posts: 36
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 23 Oct 2017, 05:19
2
mixture price is less than 40/10 -- rs 4 per kg

between 3 and 5 if less than 4 then it contains more x thats all simple
_________________
consider giving kudos if my post or question has made you think or analyse. thanks
Retired Moderator
User avatar
V
Joined: 27 Oct 2017
Posts: 1256
Location: India
Concentration: International Business, General Management
GPA: 3.64
WE: Business Development (Energy and Utilities)
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 01 May 2018, 23:06
(1) y > 4
here difference cases possible:
a) x= 5.5, y = 4.5 : x>y
b) x=y=5 : x=y
c) x= 4, y =6 : x<y

so it is not sufficient.

(2) The cost of the 10 kilograms of Material K is less than $40.
it means the cost per kg of mixture = 40/10 =4.
which is the average of cost of individual ingredients : (5+3)/2 = 4
hence if if both x = y , unit cost of mixture = 4
Since unit cost of mixture is less than 4, the ingredient of lesser cost is present in higher proportion.
Hence , x>y


Sufficient.

Answer B
_________________
Intern
Intern
avatar
B
Joined: 08 Mar 2017
Posts: 4
Location: India
Concentration: General Management, Marketing
Schools: IIMA PGPX"20
GMAT 1: 200 Q1 V1
GPA: 4
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 30 May 2018, 08:25
Hi,

1 doubt... no where in the question it is mentioned that material K consists only of material A and B. What if it has some other type of material as well ? Is this a OG question?

Thanks
Dpz
Retired Moderator
User avatar
V
Joined: 27 Oct 2017
Posts: 1256
Location: India
Concentration: International Business, General Management
GPA: 3.64
WE: Business Development (Energy and Utilities)
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 30 May 2018, 08:39
1
Hi
"If 10 kilograms of Material K consists of x kilograms of Material A and y kilograms of Material B"-It means that mixture has only 2 components A & B.
Consists of - to be made of or formed from something:Source:https://dictionary.cambridge.org/dictionary/english/consist-of-sth
It gives all the constituents.

Example:
If a Box contains 2 black and 3 white balls. We are not sure whether balls of other colors are present in the box.
But if a Box comprises/consists of 2 black and 3 white balls, it is certain that no other ball is in the box.


If you have seen any Official question testing your point of concern , please post here.


2) Yes it is an OG Question.

Dpzskr wrote:
Hi,

1 doubt... no where in the question it is mentioned that material K consists only of material A and B. What if it has some other type of material as well ? Is this a OG question?

Thanks
Dpz

_________________
Senior Manager
Senior Manager
User avatar
S
Joined: 24 Jun 2016
Posts: 344
GMAT 1: 770 Q60 V60
GPA: 4
Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post Updated on: 03 Sep 2019, 16:36
It's clear what the correct answer choice is and how to solve this problem. I think this question is odd though. Typically the 2 DS statements do not contrast each other; whereas, in this question, the two statements cannot both be right. Interesting.

And as Bunuel pointed out here below, this rule was actually not violated since the two statements can both be right as x and y do not have to be integers.
_________________
Stuck in the 600's and want to score 700+ on the GMAT?
If this describes you, we should talk. I specialize in getting motivated students into the 700's.


$90/hour as of August 2019. I am not accepting any more students for the Fall 2019 application cycle, but if you are planning to apply in 2020, feel free to reach out!


http://www.facebook.com/HanoiGMATtutor
HanoiGMATTutor@gmail.com

Originally posted by HanoiGMATtutor on 01 Sep 2019, 15:20.
Last edited by HanoiGMATtutor on 03 Sep 2019, 16:36, edited 1 time in total.
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58316
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram  [#permalink]

Show Tags

New post 01 Sep 2019, 20:57
HanoiGMATtutor wrote:
It's clear what the correct answer choice is and how to solve this problem. I think this question is odd. Typically the 2 DS statements do not contrast each other; whereas, in this question, the two statements cannot both be right. Interesting.


Actually the statements do not contradict each other. Consider x = 5.5 and y = 4.5. The would contradict if we assume that a and y are integers but we are not told that they are.
_________________
GMAT Club Bot
Re: Material A costs $3 per kilogram, and Material B costs $5 per kilogram   [#permalink] 01 Sep 2019, 20:57

Go to page    1   2    Next  [ 23 posts ] 

Display posts from previous: Sort by

Material A costs $3 per kilogram, and Material B costs $5 per kilogram

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





Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne