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

 It is currently 26 Mar 2019, 19:52

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

How many gallons of water should be added to make the

Author Message
TAGS:

Hide Tags

Intern
Joined: 27 Sep 2010
Posts: 24
How many gallons of water should be added to make the  [#permalink]

Show Tags

Updated on: 22 Jan 2011, 09:33
2
20
00:00

Difficulty:

95% (hard)

Question Stats:

32% (01:41) correct 68% (01:55) wrong based on 569 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.

Originally posted by MichelleSavina on 22 Jan 2011, 02:10.
Last edited by MichelleSavina on 22 Jan 2011, 09:33, edited 1 time in total.
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 9019
Location: Pune, India
Re: How many gallons of water should be added to make avg \$480?  [#permalink]

Show Tags

28 Jan 2011, 19:03
4
1
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

General Discussion
Manager
Joined: 03 Sep 2010
Posts: 64
Location: Israel
GMAT 1: 660 Q47 V34
GMAT 2: 670 Q48 V34
GPA: 3.2
WE: Operations (Non-Profit and Government)
Re: How many gallons of water should be added to make avg \$480?  [#permalink]

Show Tags

22 Jan 2011, 06:45
1
1
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: 24
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: 9019
Location: Pune, India
Re: How many gallons of water should be added to make avg \$480?  [#permalink]

Show Tags

27 Jan 2011, 08:02
3
1
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

Senior Manager
Joined: 08 Nov 2010
Posts: 329
Re: How many gallons of water should be added to make avg \$480?  [#permalink]

Show Tags

28 Jan 2011, 11:11
1
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?
_________________
Senior Manager
Joined: 08 Nov 2010
Posts: 329
Re: How many gallons of water should be added to make avg \$480?  [#permalink]

Show Tags

28 Jan 2011, 22:21
1
Ye, thats ez. i thought they might be asking you to reduce the price of each one of them. Thanks.
_________________
SVP
Joined: 06 Sep 2013
Posts: 1676
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/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 13807
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: 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

Co-Founder & 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: 50
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: 9019
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

Manager
Joined: 27 Dec 2013
Posts: 226
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: 79
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
Concentration: Strategy, Technology
GMAT 1: 660 Q45 V35
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: 478
Location: India
Schools: XLRI"20
GMAT 1: 700 Q50 V34
GPA: 3.5
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: 352
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: 352
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
Display posts from previous: Sort by