Author 
Message 
TAGS:

Hide Tags

Intern
Joined: 27 Sep 2010
Posts: 27

How many gallons of water should be added to make the [#permalink]
Show Tags
22 Jan 2011, 02:10
2
This post received KUDOS
21
This post was BOOKMARKED
Question Stats:
34% (01:19) correct 66% (01:15) wrong based on 520 sessions
HideShow timer Statistics
How many gallons of water should be added to make the average value of the mixture $480 per gallon. (1) 5 gallons of Milk type I is mixed with 6 gallons of Milk type II. (2) Milk of type I is $600 per gallon and the cost of type II Milk is 90% of the cost of Milk of type I.
Official Answer and Stats are available only to registered users. Register/ Login.
Last edited by MichelleSavina on 22 Jan 2011, 09:33, edited 1 time in total.



Manager
Joined: 03 Sep 2010
Posts: 70
Location: Israel
GMAT 1: 660 Q47 V34 GMAT 2: 670 Q48 V34
GPA: 3.2
WE: Operations (NonProfit and Government)

Re: How many gallons of water should be added to make avg $480? [#permalink]
Show Tags
22 Jan 2011, 06:45
1
This post was BOOKMARKED
IMO E. In the answers whater si not mentioned so we can not say how mach whater is needed...



Intern
Joined: 27 Sep 2010
Posts: 27

Re: How many gallons of water should be added to make avg $480? [#permalink]
Show Tags
23 Jan 2011, 07:06
nov79 wrote: IMO E. In the answers whater si not mentioned so we can not say how mach whater is needed... thank you nov79.... but i guess that is what we are suppose to find..... Can someone please explain it in another way....



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 7996
Location: Pune, India

Re: How many gallons of water should be added to make avg $480? [#permalink]
Show Tags
27 Jan 2011, 08:02
2
This post received KUDOS
Expert's post
1
This post was BOOKMARKED
MichelleSavina wrote: nov79 wrote: IMO E. In the answers whater si not mentioned so we can not say how mach whater is needed... thank you nov79.... but i guess that is what we are suppose to find..... Can someone please explain it in another way.... Generally water is assumed to be available free of cost but it is an assumption. The writer of the question is probably testing whether you make that assumption. You should not, in a DS question. Had it been a PS question, and an answer was required, you could have assumed it.
_________________
Karishma Veritas Prep  GMAT Instructor My Blog
Get started with Veritas Prep GMAT On Demand for $199
Veritas Prep Reviews



Senior Manager
Joined: 08 Nov 2010
Posts: 371
WE 1: Business Development

Re: How many gallons of water should be added to make avg $480? [#permalink]
Show Tags
28 Jan 2011, 11:11
1
This post received KUDOS
hmm. why is it not B? if u know the prices per gallon, u know how much water u need to add to each one in order to make them worth 480. or the questions is how much when milk I + Milk II is mixed?
_________________
GMAT Club Premium Membership  big benefits and savings



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 7996
Location: Pune, India

Re: How many gallons of water should be added to make avg $480? [#permalink]
Show Tags
28 Jan 2011, 19:03
144144 wrote: hmm. why is it not B? if u know the prices per gallon, u know how much water u need to add to each one in order to make them worth 480.
or the questions is how much when milk I + Milk II is mixed? The question says that a mixture has milk type I and milk type II and now we need to add water to make the average value = $480. So how much water needs to be added? To find the volume of water, you need to know the price of all three  milk type I, milk type II and water. You also need the volume in which milk type I and milk type II were added. B alone isn't sufficient because it just gives you the price of milk type I and type II. We don't know the volume of these two. Even when you have both statements 1 and 2, you do not know the price of water (which may not be assumed to be available free of cost)
_________________
Karishma Veritas Prep  GMAT Instructor My Blog
Get started with Veritas Prep GMAT On Demand for $199
Veritas Prep Reviews



Senior Manager
Joined: 08 Nov 2010
Posts: 371
WE 1: Business Development

Re: How many gallons of water should be added to make avg $480? [#permalink]
Show Tags
28 Jan 2011, 22:21
Ye, thats ez. i thought they might be asking you to reduce the price of each one of them. Thanks.
_________________
GMAT Club Premium Membership  big benefits and savings



Current Student
Joined: 06 Sep 2013
Posts: 1949
Concentration: Finance

Re: How many gallons of water should be added to make avg $480? [#permalink]
Show Tags
16 Dec 2013, 12:08
VeritasPrepKarishma wrote: MichelleSavina wrote: nov79 wrote: IMO E. In the answers whater si not mentioned so we can not say how mach whater is needed... thank you nov79.... but i guess that is what we are suppose to find..... Can someone please explain it in another way.... Generally water is assumed to be available free of cost but it is an assumption. The writer of the question is probably testing whether you make that assumption. You should not, in a DS question. Had it been a PS question, and an answer was required, you could have assumed it. Hm.. that's confusing cause I remember doing a question where I had to assume that water was free of cost and it was correct anyway. I'll take it into account from now on Cheers! J



EMPOWERgmat Instructor
Status: GMAT Assassin/CoFounder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 11281
Location: United States (CA)
GRE 1: 340 Q170 V170

Re: How many gallons of water should be added to make the [#permalink]
Show Tags
25 Apr 2015, 17:23
Hi All, Is information missing from the prompt? Based on the two Facts, it appears that we're meant to mix two types of milk with water, but without information in the prompt to establish what the 'parameters' of the question are, this prompt is essentially nonsense. GMAT assassins aren't born, they're made, Rich
_________________
760+: Learn What GMAT Assassins Do to Score at the Highest Levels Contact Rich at: Rich.C@empowergmat.com
Rich Cohen
CoFounder & GMAT Assassin
Special Offer: Save $75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee www.empowergmat.com/
***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************



Manager
Joined: 08 Oct 2013
Posts: 51

Re: How many gallons of water should be added to make the [#permalink]
Show Tags
26 Jun 2015, 12:19
MichelleSavina wrote: How many gallons of water should be added to make the average value of the mixture $480 per gallon.
(1) 5 gallons of Milk type I is mixed with 6 gallons of Milk type II. (2) Milk of type I is $600 per gallon and the cost of type II Milk is 90% of the cost of Milk of type I. If we assume that water is free, then the answer is C. ?



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 7996
Location: Pune, India

Re: How many gallons of water should be added to make the [#permalink]
Show Tags
28 Jun 2015, 21:56
AjChakravarthy wrote: MichelleSavina wrote: How many gallons of water should be added to make the average value of the mixture $480 per gallon.
(1) 5 gallons of Milk type I is mixed with 6 gallons of Milk type II. (2) Milk of type I is $600 per gallon and the cost of type II Milk is 90% of the cost of Milk of type I. If we assume that water is free, then the answer is C. ? Yes, then you can solve it. Avg Price = (Price1 * w1 + Price2 * w2 + Price3 * w3)/(w1 + w2 + w3) 480 = (600*5 + 540*6 + 0)/(5 + 6 + w) Solve for w, the amount of water added.
_________________
Karishma Veritas Prep  GMAT Instructor My Blog
Get started with Veritas Prep GMAT On Demand for $199
Veritas Prep Reviews



Senior Manager
Joined: 27 Dec 2013
Posts: 296

Re: How many gallons of water should be added to make the [#permalink]
Show Tags
29 Jun 2015, 07:08
Hi karishma I did exactly the same way as you did, but realised that the assumption of cost of water is not warranted. I hope question such as this would be on real test.. So Equivocal... the answer shifts from C to E. VeritasPrepKarishma wrote: AjChakravarthy wrote: MichelleSavina wrote: How many gallons of water should be added to make the average value of the mixture $480 per gallon.
(1) 5 gallons of Milk type I is mixed with 6 gallons of Milk type II. (2) Milk of type I is $600 per gallon and the cost of type II Milk is 90% of the cost of Milk of type I. If we assume that water is free, then the answer is C. ? Yes, then you can solve it. Avg Price = (Price1 * w1 + Price2 * w2 + Price3 * w3)/(w1 + w2 + w3) 480 = (600*5 + 540*6 + 0)/(5 + 6 + w) Solve for w, the amount of water added.
_________________
Kudos to you, for helping me with some KUDOS.



Manager
Joined: 24 May 2013
Posts: 85

Re: How many gallons of water should be added to make the [#permalink]
Show Tags
02 Apr 2016, 13:02
Assumed water available free of cost and got C.



Manager
Joined: 27 Aug 2014
Posts: 55
Location: Canada
Concentration: Strategy, Technology
GPA: 3.66
WE: Consulting (Consulting)

Re: How many gallons of water should be added to make the [#permalink]
Show Tags
29 May 2017, 21:14
Have there been instances where we need to make such assumptions? that water costs money too?



Senior Manager
Joined: 02 Apr 2014
Posts: 451

Re: How many gallons of water should be added to make the [#permalink]
Show Tags
23 Oct 2017, 10:26
Good Question, Teased me I answered C assuming water is free of cost. Need to bring in CR techniques in DS as well.



Senior Manager
Joined: 15 Jan 2017
Posts: 360

Re: How many gallons of water should be added to make the [#permalink]
Show Tags
18 Nov 2017, 14:05
VeritasPrepKarishma wrote: 144144 wrote: hmm. why is it not B? if u know the prices per gallon, u know how much water u need to add to each one in order to make them worth 480.
or the questions is how much when milk I + Milk II is mixed? The question says that a mixture has milk type I and milk type II and now we need to add water to make the average value = $480. So how much water needs to be added? To find the volume of water, you need to know the price of all three  milk type I, milk type II and water. You also need the volume in which milk type I and milk type II were added. B alone isn't sufficient because it just gives you the price of milk type I and type II. We don't know the volume of these two. Even when you have both statements 1 and 2, you do not know the price of water (which may not be assumed to be available free of cost) But doesn't it say PER GALLON? So essentially B says > 600 + 540 = $1140 for just milk (say 2 gallons). So one gallon (total) would be 1140/2 which is $570. So to bring it down to $480, we would know how much dilution is required PER GALLON? (Sorry for caps, just trying to emphasize, not yell ). Also, in questions where water price (or anything else) is not to be assumed? Thank you!



Senior Manager
Joined: 15 Jan 2017
Posts: 360

Re: How many gallons of water should be added to make the [#permalink]
Show Tags
13 Dec 2017, 07:57
VeritasPrepKarishma wrote: MichelleSavina wrote: nov79 wrote: IMO E. In the answers whater si not mentioned so we can not say how mach whater is needed... thank you nov79.... but i guess that is what we are suppose to find..... Can someone please explain it in another way.... Generally water is assumed to be available free of cost but it is an assumption. The writer of the question is probably testing whether you make that assumption. You should not, in a DS question. Had it been a PS question, and an answer was required, you could have assumed it. Oh yes, I did assume its free, and picked B. [A was evidently insufficient]




Re: How many gallons of water should be added to make the
[#permalink]
13 Dec 2017, 07:57






