GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

 It is currently 19 Jan 2020, 14:36 ### 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

#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.  # What is the ratio of x:y:z?

Author Message
TAGS:

### Hide Tags

Senior Manager  Joined: 25 Nov 2006
Posts: 299
Schools: St Gallen, Cambridge, HEC Montreal
What is the ratio of x:y:z?  [#permalink]

### Show Tags

4
24 00:00

Difficulty:   45% (medium)

Question Stats: 59% (01:20) correct 41% (01:12) wrong based on 527 sessions

### HideShow timer Statistics

What is the ratio of x:y:z?

(1) xy = 14
(2) yz = 21
Verbal Forum Moderator B
Joined: 10 Oct 2012
Posts: 578
Re: What is the ratio of x:y:z?  [#permalink]

### Show Tags

6
josemnz83 wrote:
I'm not quite sure. Perhaps someone can explain it to us. I also rewrote both proportions in terms of y.

dave785 wrote:
umm... I got C.

if x*y = 14, then x = 14 / y

if y*z = 21, then z = 21 / y

therefore, we can put the whole ratio in terms of y:

14/y : y : 21/y

why does this not work?

It doesn't work for the reason that there is a variable in the final expression. When the question is asking for the value of the ratio x:y:z, it means that we should get a unique numerical value with the given fact statement(s). One could plug in y = 1 and get the ratio as 14:1:21. Yet again, someone else might plugin y = 7 and get the ratio as 2:7:3.
Thus the scope of getting two different numeric values makes it insufficient.
_________________
##### General Discussion
Manager  Joined: 20 Jun 2007
Posts: 106

### Show Tags

E - even with both values, there are still multiple possible solutions.
Director  Joined: 09 Aug 2006
Posts: 546

### Show Tags

lumone wrote:
What is the ratio of x:y:z?

(1) xy=14
(2) yz=21

E.

Clear that 1 and 2 are insuff by themselves.

Together:
x = 2, y = 7, z = 3 or x = 1, y = 14, z =21/14
insuff.
Manager  Joined: 01 Jul 2012
Posts: 79
Location: United States
GMAT 1: 510 Q34 V28
GMAT 2: 580 Q35 V35
GMAT 3: 640 Q34 V44
GMAT 4: 690 Q43 V42
GPA: 3.61
WE: Education (Education)

### Show Tags

1
On the Total GMAT book Sackmann explains that to find the values of x,y, and z we would need THREE equations and that to find the three part ratio x:y:z we would need TWO ratios. Can someone please elaborate on what exactly that means?

GK_Gmat wrote:
lumone wrote:
What is the ratio of x:y:z?

(1) xy=14
(2) yz=21

E.

Clear that 1 and 2 are insuff by themselves.

Together:
x = 2, y = 7, z = 3 or x = 1, y = 14, z =21/14
insuff.
Manager  Joined: 09 Apr 2013
Posts: 187
Location: United States
Concentration: Finance, Economics
GMAT 1: 710 Q44 V44
GMAT 2: 740 Q48 V44
GPA: 3.1
WE: Sales (Mutual Funds and Brokerage)
Re: What is the ratio of x:y:z?  [#permalink]

### Show Tags

umm... I got C.

if x*y = 14, then x = 14 / y

if y*z = 21, then z = 21 / y

therefore, we can put the whole ratio in terms of y:

14/y : y : 21/y

why does this not work?
Manager  Joined: 01 Jul 2012
Posts: 79
Location: United States
GMAT 1: 510 Q34 V28
GMAT 2: 580 Q35 V35
GMAT 3: 640 Q34 V44
GMAT 4: 690 Q43 V42
GPA: 3.61
WE: Education (Education)
Re: What is the ratio of x:y:z?  [#permalink]

### Show Tags

I'm not quite sure. Perhaps someone can explain it to us. I also rewrote both proportions in terms of y.

dave785 wrote:
umm... I got C.

if x*y = 14, then x = 14 / y

if y*z = 21, then z = 21 / y

therefore, we can put the whole ratio in terms of y:

14/y : y : 21/y

why does this not work?
Intern  Joined: 22 Jun 2013
Posts: 3
Concentration: Finance, Other
GMAT Date: 07-20-2013
Re: What is the ratio of x:y:z?  [#permalink]

### Show Tags

3
1
Hey Lumone,

The way I figured it out was to prove that there was more than 1 answer to each ratio

(1) xy = 14

One Way: x=2, y=7
Second Way: x=14, y=1

Therefore insufficient

(2) yz = 21

Same here

One Way: x=3, y=7
Second Way: x=21, y=1

insufficient again.

Now it's either C or E

One Way: x=2, y=7, z=3... This satisfies both 1 and 2
Second Way: x=14, y=1, z=21.. This also satisfies both 1 and 2

Insufficient... go with E. Hope this helps!!
Manager  Joined: 01 Jul 2012
Posts: 79
Location: United States
GMAT 1: 510 Q34 V28
GMAT 2: 580 Q35 V35
GMAT 3: 640 Q34 V44
GMAT 4: 690 Q43 V42
GPA: 3.61
WE: Education (Education)
Re: What is the ratio of x:y:z?  [#permalink]

### Show Tags

How is this question different from a question that asks for the value of p if p=r/3q and then tells you that the value of r=2q? Is it because we can come up with an exact value for the equation?

I was under the impression that one needs to have three equations when dealing with three variables. Here we only have 2 equations (the original statement and r=2q?

mau5 wrote:
josemnz83 wrote:
I'm not quite sure. Perhaps someone can explain it to us. I also rewrote both proportions in terms of y.

dave785 wrote:
umm... I got C.

if x*y = 14, then x = 14 / y

if y*z = 21, then z = 21 / y

therefore, we can put the whole ratio in terms of y:

14/y : y : 21/y

why does this not work?

It doesn't work for the reason that there is a variable in the final expression. When the question is asking for the value of the ratio x:y:z, it means that we should get a unique numerical value with the given fact statement(s). One could plug in y = 1 and get the ratio as 14:1:21. Yet again, someone else might plugin y = 7 and get the ratio as 2:7:3.
Thus the scope of getting two different numeric values makes it insufficient.
Verbal Forum Moderator B
Joined: 10 Oct 2012
Posts: 578
Re: What is the ratio of x:y:z?  [#permalink]

### Show Tags

2
josemnz83 wrote:
How is this question different from a question that asks for the value of p if p=r/3q and then tells you that the value of r=2q? Is it because we can come up with an exact value for the equation?

Exactly. It is because you can get a unique numeric value for p. Also, with the help of these two equations, we can only solve for the value of only one variable, i.e. p, and nothing else.

Quote:
I was under the impression that one needs to have three equations when dealing with three variables. Here we only have 2 equations (the original statement and r=2q?

What you are saying is true, most of the times. However, there are times, when you have 3 equations and 3 variables and still get no unique solution, or get infinitely many solutions. Also, there are times when a single equation with 2 variables might give the value of both the variables under special conditions.[For example, when the variables can only assume integral values].

For example, 2x+3y=5, you can arrive at many integral solutions for (x,y) for example (1,1),(-2,3) etc. For the given context, there might be an additional restriction;like the value of both the variables should be positive,etc in the problem, which would then help you to zero-in on a unique solution. Ergo, it will be a good idea to keep in mind that apart from the general rule of N equations and N variables, there are many variants possible, depending on the context of the given problem.

Hope this helps.
_________________
Intern  Joined: 22 Nov 2015
Posts: 17
Re: What is the ratio of x:y:z?  [#permalink]

### Show Tags

The question in here asks for values of x:y:z
and hence we require unique solution which is what we dont get from either statement (1) or statement(2) individually
And even after combining, we dnt get unique solution.
So ans is : E
Senior Manager  S
Joined: 08 Dec 2015
Posts: 282
GMAT 1: 600 Q44 V27
What is the ratio of x:y:z?  [#permalink]

### Show Tags

Guys, can you please explain how are you coming up with numerical values for the variables? Isn't this supposed to be a ratio?

1) + 2) together

y=14/x so (14z/x = 21) so 3X=2z got one relationship (ratio)

After this I cant really find anything solid for Y, there seem to be endless ways to plug variable back and forth, but I am not 100% sure that it is E.

So how can I be 100% sure here?
Manager  B
Joined: 05 Oct 2014
Posts: 128
Location: India
Concentration: General Management, Strategy
GMAT 1: 580 Q41 V28
GPA: 3.8
WE: Project Management (Energy and Utilities)
Re: What is the ratio of x:y:z?  [#permalink]

### Show Tags

lumone wrote:
What is the ratio of x:y:z?

(1) xy = 14
(2) yz = 21

I think, reason behind the Correct Answer E is because the question does not specifically mention whether x,y or z is integer or not.

If it is Integer, then obviously the correct answer would have been C.

In this case, x:y:z can be 2:7:3 or 1:14:21/14 . So no unique solution.

gmatbusters : Pls correct me if I am wrong
Retired Moderator V
Joined: 27 Oct 2017
Posts: 1396
Location: India
GPA: 3.64
WE: Business Development (Energy and Utilities)
What is the ratio of x:y:z?  [#permalink]

### Show Tags

1
yes if x, y, z had been integers, it would have been C.

But here x, y, z need not be integers, iliavko, This question can be easily understood by this
Attachment: gc .jpg [ 120.94 KiB | Viewed 429 times ]

merajul wrote:
lumone wrote:
What is the ratio of x:y:z?

(1) xy = 14
(2) yz = 21

I think, reason behind the Correct Answer E is because the question does not specifically mention whether x,y or z is integer or not.

If it is Integer, then obviously the correct answer would have been C.

In this case, x:y:z can be 2:7:3 or 1:14:21/14 . So unique solution.

gmatbusters : Pls correct me if I am wrong

Attachment: gc .jpg [ 120.94 KiB | Viewed 429 times ]

_________________
Manager  B
Joined: 05 Oct 2014
Posts: 128
Location: India
Concentration: General Management, Strategy
GMAT 1: 580 Q41 V28
GPA: 3.8
WE: Project Management (Energy and Utilities)
Re: What is the ratio of x:y:z?  [#permalink]

### Show Tags

gmatbusters wrote:
yes if x, y, z had been integers, it would have been C.

But here x, y, z need not be integers, This question can be easily understood by this
Attachment:
gc%20.jpg

merajul wrote:
lumone wrote:
What is the ratio of x:y:z?

(1) xy = 14
(2) yz = 21

I think, reason behind the Correct Answer E is because the question does not specifically mention whether x,y or z is integer or not.

If it is Integer, then obviously the correct answer would have been C.

In this case, x:y:z can be 2:7:3 or 1:14:21/14 . So unique solution.

gmatbusters : Pls correct me if I am wrong

Attachment:
gc .jpg Re: What is the ratio of x:y:z?   [#permalink] 12 Dec 2019, 21:59
Display posts from previous: Sort by

# What is the ratio of x:y:z?  