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

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Manager
Joined: 06 Aug 2010
Posts: 220
Location: Boston
Re: Material A costs $3 per kilogram, and material B costs$5 per kilogram [#permalink]

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21 Sep 2010, 11:33
udaymathapati 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. I did it slightly differently. We know x + y = 10... (1) Clearly insufficient. (2) If x = y = 5, then the 10kg of material K costs ($3*5) + ($5*5) =$40. Since x costs less than y, the more you increase x, the less material K will cost. So if K costs less than $40, x must be greater than 5, and so y is less than 5. Sufficient. Manager Joined: 26 Jul 2010 Posts: 103 Location: India Concentration: Operations, General Management Schools: IIMA (M) GMAT 1: 640 Q48 V29 GMAT 2: 670 Q49 V31 WE: Supply Chain Management (Military & Defense) Re: Material A costs$3 per kilogram, and material B costs $5 [#permalink] ### Show Tags 22 Apr 2011, 23:27 answer is B question simplifies to x+y=10 is x>y 1. y >4 is x> y so we have y=4.5 then x= 5.5 yes y= 5 then x= 5 no y= 6 then x=4 no in sufficent 2. gives 3x+5y<40 and x,y>0 so we have 3(10-y) +5y < 40 y<5 now for all values of y<5 === x> y since x+y=10 hence B _________________ lets start again Math Forum Moderator Joined: 20 Dec 2010 Posts: 2010 Re: Material A costs$3 per kilogram, and material B costs $5 [#permalink] ### Show Tags 22 Apr 2011, 23:50 tejal777 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.

umm...(D) is it??

(1) y>4
y=4.1kg; x=4.2kg
x=4.2kg; y=4.2kg
Not Sufficient.

(2)
y=1kg; x=2kg; cost=2*3+1*5=11<40
y=2kg; x=1kg; cost=2*1+2*5=12<40
Not Sufficient.

Combining both:
y=4.5;x=5; cost=5*3+4.5*5=15+22.5=37.5<40
y=5;x=1; cost=1*3+5*5=3+25=28<40
Not Sufficient.

Ans:"E"

P.S.: It is not given that material k contains ONLY material A and B. Had it been given, "B" alone would have sufficed.
_________________
Manager
Joined: 26 Jul 2010
Posts: 103
Location: India
Concentration: Operations, General Management
Schools: IIMA (M)
GMAT 1: 640 Q48 V29
GMAT 2: 670 Q49 V31
WE: Supply Chain Management (Military & Defense)
Re: Material A costs $3 per kilogram, and material B costs$5 per kilogram [#permalink]

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22 Apr 2011, 23:57

remember x+y=10 in question statement
_________________

lets start again

Manager
Joined: 26 Jul 2010
Posts: 103
Location: India
Concentration: Operations, General Management
Schools: IIMA (M)
GMAT 1: 640 Q48 V29
GMAT 2: 670 Q49 V31
WE: Supply Chain Management (Military & Defense)
Re: Material A costs $3 per kilogram, and material B costs$5 [#permalink]

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23 Apr 2011, 02:54
fluke wrote:
tejal777 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. umm...(D) is it?? (1) y>4 y=4.1kg; x=4.2kg x=4.2kg; y=4.2kg Not Sufficient. (2) y=1kg; x=2kg; cost=2*3+1*5=11<40 y=2kg; x=1kg; cost=2*1+2*5=12<40 Not Sufficient. Combining both: y=4.5;x=5; cost=5*3+4.5*5=15+22.5=37.5<40 y=5;x=1; cost=1*3+5*5=3+25=28<40 Not Sufficient. Ans:"E" P.S.: It is not given that material k contains ONLY material A and B. Had it been given, "B" alone would have sufficed. if it says item k consist of A and B i hope it means it consists of a and b only otherwise so many GMAT would have answer as E this question will too simple to answer if assume what you are saying AM i correct _________________ lets start again Math Forum Moderator Joined: 20 Dec 2010 Posts: 2010 Re: Material A costs$3 per kilogram, and material B costs $5 [#permalink] ### Show Tags 23 Apr 2011, 03:20 kamalkicks wrote: if it says item k consist of A and B i hope it means it consists of a and b only otherwise so many GMAT would have answer as E this question will too simple to answer if assume what you are saying AM i correct My intention is not to debunk this question as many agree with the OA to be "B", making your interpretation correct . But it would definitely be less ambiguous if the author mentioned the fact explicitly, at least for me. I consider all of the three statements correct: Sulphuric Acid, $$H_2SO_4$$, consists hydrogen and sulphur. Water, $$H_2O$$, consists only hydrogen and oxygen. Water, $$H_2O$$, consists hydrogen and oxygen. _________________ Director 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: 900 Re: Material A costs$3 per kilogram, and material B costs $5 per kilogram [#permalink] ### Show Tags 23 Apr 2011, 05:13 1 This post received KUDOS The question can be rephrased as - x > y? Or (10 - y) > y Or y < 5 ? Is y < 5 ? 1. Insufficient. y can be 6 or y can be 4.5 2. 3x + 5y < 40 and we know that x = 10 - y 3(10- y) + 5y < 40 30 -3y + 5y < 40 2y < 10 y < 5 Sufficient Answer B udaymathapati 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.
Director
Joined: 01 Feb 2011
Posts: 755
Re: Material A costs $3 per kilogram, and material B costs$5 per kilogram [#permalink]

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23 Apr 2011, 07:26
x+y = 10

x>y?
10-y>y => y<5?

1. Insufficient

y>4 doesnt mean y <5.

y = 4.5 <5
y = 5 is not less than 5

2. Sufficient

3x+5y <40

=> 3(10-y)+5y <40 => y <5

Manager
Joined: 11 Dec 2010
Posts: 115
WE: Consulting (Consulting)
Re: Material A costs $3 per kilogram, and material B costs$5 per kilogram [#permalink]

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23 Apr 2011, 07:58
Statement 1 - Not possible to get any single answer as y could be 4.5 or even 5.5
Statement 2 - If x=y, then the cost of 10 kgs would be 40
If it is less than 40 means that quantity of y (higher priced item) is less than X (lower priced)

So with statement B, a unique solution can be derived

No need for equations... only think logically...
SVP
Joined: 16 Nov 2010
Posts: 1663
Location: United States (IN)
Concentration: Strategy, Technology
Re: Material A costs $3 per kilogram, and material B costs$5 per kilogram [#permalink]

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24 Apr 2011, 07:36
3x + 5y

x + y = 10

(1) y > 4

But x = 5, y = 5 is possible

y = 4.5 x = 5.5 is possible

(2)

3x + 5y < 40

3(10 - y) + 5y < 40

2y < 10

y < 5

So x > y - sufficient

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SVP
Joined: 16 Nov 2010
Posts: 1663
Location: United States (IN)
Concentration: Strategy, Technology
Re: Material A costs $3 per kilogram, and material B costs$5 [#permalink]

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24 Apr 2011, 07:39
3x + 5y

x + y = 10

(1) y > 4

But x = 5, y = 5 is possible

y = 4.5 x = 5.5 is possible

(2)

3x + 5y < 40

3(10 - y) + 5y < 40

2y < 10

y < 5

So x > y - sufficient

_________________

Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant)

GMAT Club Premium Membership - big benefits and savings

Director
Joined: 01 Feb 2011
Posts: 755
Re: Material A costs $3 per kilogram, and material B costs$5 [#permalink]

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24 Apr 2011, 08:11
1. Not sufficient

y > 4

y 6 4.5
x 4 5.5

x<y x>y

2. Sufficient

3x +5y <40

30-3y+5y <40
y<5

y 4.5 4

x 5.5 6

x>y x>y

Manager
Status: ==GMAT Ninja==
Joined: 08 Jan 2011
Posts: 242
Schools: ISB, IIMA ,SP Jain , XLRI
WE 1: Aditya Birla Group (sales)
WE 2: Saint Gobain Group (sales)
Re: Material A costs $3 per kilogram, and material B costs$5 [#permalink]

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24 Apr 2011, 11:52
1
KUDOS
fluke wrote:
tejal777 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. umm...(D) is it?? (1) y>4 y=4.1kg; x=4.2kg x=4.2kg; y=4.2kg Not Sufficient. (2) y=1kg; x=2kg; cost=2*3+1*5=11<40 y=2kg; x=1kg; cost=2*1+2*5=12<40 Not Sufficient. Combining both: y=4.5;x=5; cost=5*3+4.5*5=15+22.5=37.5<40 y=5;x=1; cost=1*3+5*5=3+25=28<40 Not Sufficient. Ans:"E" P.S.: It is not given that material k contains ONLY material A and B. Had it been given, "B" alone would have sufficed. Dear Fluke now that we have that the total quantity is 10 kg so clearly y=10-x so total cost of the mixture 3x+5(10-x)=50-2x (1) y>4 i.e. 10-x>4 so x<6 clearly there can be values of both x & y =5 so in this case x=y no sufficient (2) says 50-2x<40 so x>5 so by this we get y<5 so clearly y<x to make the cost less than 40 B is the answer please correct me _________________ WarLocK _____________________________________________________________________________ The War is oNNNNNNNNNNNNN for 720+ see my Test exp here http://gmatclub.com/forum/my-test-experience-111610.html do not hesitate me giving kudos if you like my post. Manager Joined: 23 Oct 2011 Posts: 84 Re: Material A costs$3 per kilogram, and material B costs $5 [#permalink] ### Show Tags 25 Oct 2011, 07:01 fluke wrote: Warlock007 wrote: Dear Fluke now that we have that the total quantity is 10 kg so clearly y=10-x so total cost of the mixture 3x+5(10-x)=50-2x (1) y>4 i.e. 10-x>4 so x<6 clearly there can be values of both x & y =5 so in this case x=y no sufficient (2) says 50-2x<40 so x>5 so by this we get y<5 so clearly y<x to make the cost less than 40 B is the answer please correct me You are correct. I just abortively tried to make a point. Fluke? why is the correct answer B? From your previous post I understood that it is E. I agree with your previous post where you said that it should have said "it consists of ONLY x and y..." to be correct. Could you please elaborate on that? Math Forum Moderator Joined: 20 Dec 2010 Posts: 2010 Re: Material A costs$3 per kilogram, and material B costs $5 [#permalink] ### Show Tags 25 Oct 2011, 09:56 SonyGmat wrote: Fluke? why is the correct answer B? From your previous post I understood that it is E. I agree with your previous post where you said that it should have said "it consists of ONLY x and y..." to be correct. Could you please elaborate on that? Precisely so. Answer should be "E" as per my interpretation of the wordings. I just surrendered half-heartedly to "B" :D I recommend you skip this question. GMAT's wordings will be very precise and without ambiguity. _________________ Director Status: No dream is too large, no dreamer is too small Joined: 14 Jul 2010 Posts: 633 Re: Material A costs$3 per kilogram, and material B costs $5 [#permalink] ### Show Tags 11 Dec 2011, 10:13 This is an og problem DS 101 12th edition. Ans. B subhashghosh did good job. _________________ Collections:- PSof OG solved by GC members: http://gmatclub.com/forum/collection-ps-with-solution-from-gmatclub-110005.html DS of OG solved by GC members: http://gmatclub.com/forum/collection-ds-with-solution-from-gmatclub-110004.html 100 GMAT PREP Quantitative collection http://gmatclub.com/forum/gmat-prep-problem-collections-114358.html Collections of work/rate problems with solutions http://gmatclub.com/forum/collections-of-work-rate-problem-with-solutions-118919.html Mixture problems in a file with best solutions: http://gmatclub.com/forum/mixture-problems-with-best-and-easy-solutions-all-together-124644.html Intern Joined: 14 Oct 2011 Posts: 4 Re: Material A costs$3 per kilogram, and material B costs $5 [#permalink] ### Show Tags 16 Feb 2012, 08:08 tejal777 wrote: Ohh!! People this is why I bow down to this forum...Thank you..! Tejal: Please don't get bow down. The answere is E. Take 1st statement: X= 5.1 and Y= 4.9, here X>Y X= 5 and Y=5 X=Y X=4 and Y= 6 X<Y Hence 1 is not sufficient Take Statement 2: 3X+4Y< 40 Lets take X=6 and Y=4 total cost = 34<40 Take x= 4 and Y= 6 Total Cost= 38<40 Cannot determined x and y,henec not sufficient Combine both: Y=5,X=5 3X+4Y= 33<40 Y= 4.1 X= 5.9 3X+4Y= 34.1 <40 Not sufficient. Some of my friends have argued that there is nothing mentioned like mixture consists of only A and B. This factor would add further uncertainity. Hence E is the best answere according to me. Math Expert Joined: 02 Sep 2009 Posts: 39672 Re: Material A costs$3 per kilogram, and material B costs $5 [#permalink] ### Show Tags 16 Feb 2012, 09:45 jaymin1986 wrote: tejal777 wrote: Ohh!! People this is why I bow down to this forum...Thank you..! Tejal: Please don't get bow down. The answere is E. Take 1st statement: X= 5.1 and Y= 4.9, here X>Y X= 5 and Y=5 X=Y X=4 and Y= 6 X<Y Hence 1 is not sufficient Take Statement 2: 3X+4Y< 40 Lets take X=6 and Y=4 total cost = 34<40 Take x= 4 and Y= 6 Total Cost= 38<40 Cannot determined x and y,henec not sufficient Combine both: Y=5,X=5 3X+4Y= 33<40 Y= 4.1 X= 5.9 3X+4Y= 34.1 <40 Not sufficient. Some of my friends have argued that there is nothing mentioned like mixture consists of only A and B. This factor would add further uncertainity. Hence E is the best answere according to me. The OA for this question is B, not E. Open discussion of the question is here: material-a-costs-3-per-kilogram-and-material-b-costs-82349.html In case of any question please continue discussion there. _________________ GMAT Club Legend Joined: 09 Sep 2013 Posts: 15968 Re: Material A costs$3 per kilogram, and material B costs $5 [#permalink] ### Show Tags 13 Oct 2014, 08:24 Hello from the GMAT Club BumpBot! Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos). Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email. _________________ Director Joined: 23 Jan 2013 Posts: 585 Schools: Cambridge'16 Re: Material A costs$3 per kilogram, and material B costs $5 per kilogram [#permalink] ### Show Tags 27 Nov 2014, 22:52 St1. INSUFFICIENT St.2 means that mixture average cost is 40/10<4$/kg.

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