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If w/x = 2/3 and w/y = 8/15, then (x + y)/y =

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If w/x = 2/3 and w/y = 8/15, then (x + y)/y =  [#permalink]

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New post 27 Feb 2015, 04:54
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A
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D
E

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Re: If w/x = 2/3 and w/y = 8/15, then (x + y)/y =  [#permalink]

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New post Updated on: 27 Feb 2015, 18:25
1
Ratio 1:

3w = 2x
multiple of 5:
15w = 10x

Ratio 2:

15w = 8y

LCM of 8, 15, 10 = 120.

Ratio 1 : 15(8) = 10(12)
therefore x = 12

Ratio 2 : 15(8) = 8(15)
therefore y = 15

(15+12)/15 is reduced to 9/5.

Answer E. 9/5

Posted from my mobile device

Originally posted by ak1802 on 27 Feb 2015, 07:22.
Last edited by ak1802 on 27 Feb 2015, 18:25, edited 1 time in total.
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Re: If w/x = 2/3 and w/y = 8/15, then (x + y)/y =  [#permalink]

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New post 27 Feb 2015, 08:52
1
Bunuel wrote:
If w/x = 2/3 and w/y = 8/15, then (x + y)/y =

A. 4/5
B. 6/5
C. 7/5
D. 8/5
E. 9/5


Kudos for a correct solution.


We need (x+y)/y
= x/y + 1
Now, w/x = 2/3 => x = (3w)/2
Also, w/y = 8/15 => y = (15w)/8
We need x/y + 1
= (3w/2) / (15w/8) + 1
= (3w/2) * (8/15w) + 1
= 4/5 + 1
= 9/5
Hence option E.

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Re: If w/x = 2/3 and w/y = 8/15, then (x + y)/y =  [#permalink]

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New post 27 Feb 2015, 13:21
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Hi All,

While many Test Takers would go about solving this problem with Algebra, TESTing VALUES provides an easy approach.

We're told that W/X = 2/3 and W/Y = 8/15

Given these two ratios, we know that W is a multiple of 2 and a multiple of 8. The simplest value for W is 8....

W = 8
X = 12
Y = 15

Using these values, we can now answer the question: (X+Y)/Y = .....

(12 + 15)/15 = 27/15 = 9/5

Final Answer:

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Re: If w/x = 2/3 and w/y = 8/15, then (x + y)/y =  [#permalink]

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New post 27 Feb 2015, 18:26
EMPOWERgmatRichC wrote:
Hi All,

While many Test Takers would go about solving this problem with Algebra, TESTing VALUES provides an easy approach.

We're told that W/X = 2/3 and W/Y = 8/15

Given these two ratios, we know that W is a multiple of 2 and a multiple of 8. The simplest value for W is 8....

W = 8
X = 12
Y = 15

Using these values, we can now answer the question: (X+Y)/Y = .....

(12 + 15)/15 = 27/15 = 9/5

Final Answer:

GMAT assassins aren't born, they're made,
Rich


I took the same approach, however by finding the LCM of all the numbers involved you aren't necessarily "testing" numbers. The integer you found WILL work.
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Re: If w/x = 2/3 and w/y = 8/15, then (x + y)/y =  [#permalink]

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New post 27 Feb 2015, 18:41
Hi ak1802,

I didn't have to use the LCM; I chose to TEST VALUES that were the easiest AND fit the 'restrictions' that we were given. In a 'TEST VALUES' prompt, there may or may not be 'restrictions.' If there are few/no restrictions, then you have more freedom to TEST values that strike you as easy to work with. The more restrictions there are, the more specific you have to be with the VALUES that you TEST.

Here's another example that doesn't use the LCM....

W/X = 2/3 and W/Y = 8/15

W = 16
X = 24
Y = 30

(X+Y)/Y = (24+30)/30 = 54/30 = 9/5

It still gets us the correct answer.

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Rich
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Re: If w/x = 2/3 and w/y = 8/15, then (x + y)/y =  [#permalink]

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New post 27 Feb 2015, 18:49
EMPOWERgmatRichC wrote:
Hi ak1802,

I didn't have to use the LCM; I chose to TEST VALUES that were the easiest AND fit the 'restrictions' that we were given. In a 'TEST VALUES' prompt, there may or may not be 'restrictions.' If there are few/no restrictions, then you have more freedom to TEST values that strike you as easy to work with. The more restrictions there are, the more specific you have to be with the VALUES that you TEST.

Here's another example that doesn't use the LCM....

W/X = 2/3 and W/Y = 8/15

W = 16
X = 24
Y = 30

(X+Y)/Y = (24+30)/30 = 54/30 = 9/5

It still gets us the correct answer.

GMAT assassins aren't born, they're made,
Rich


All I'm saying is that the value wasn't necessarily being "tested", given the restrictions on it. You found the LCM of X, Y, and Z. If this number was calculated properly, you aren't really "testing" an integer. This integer WILL fit the given rations.

I suppose it's just the semantics of "testing", which I associate some level of uncertainty with. Whereas in this case, there is no uncertainty, as the number both of us used was the LCM.

Don't get me wrong, I am a big supporter of using SMART numbers when "testing" for solutions. However I suppose I just felt that classifying this as testing sounds misleading.
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Re: If w/x = 2/3 and w/y = 8/15, then (x + y)/y =  [#permalink]

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Re: If w/x = 2/3 and w/y = 8/15, then (x + y)/y =  [#permalink]

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New post 14 Nov 2017, 05:54
Bunuel wrote:
Bunuel wrote:
If w/x = 2/3 and w/y = 8/15, then (x + y)/y =

A. 4/5
B. 6/5
C. 7/5
D. 8/5
E. 9/5


Kudos for a correct solution.


MAGOOSH OFFICIAL SOLUTION:
Attachment:
wxandy_text.PNG



Correct Answer: E
(x+y)/y = (x/y) +1
so, if we need to get the value of x/y

by dividing w/x by w/y we get the following:

w/x ÷ w/y = w/x *y/w=y/x = 2/3*15/8= 5/4

Therefore x/y=4/5
(x+y)/y= (x/y)+1= 4/5+5/5=9/5 ==> E
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Re: If w/x = 2/3 and w/y = 8/15, then (x + y)/y =  [#permalink]

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New post 14 Nov 2017, 08:34
Bunuel wrote:
If w/x = 2/3 and w/y = 8/15, then (x + y)/y =

A. 4/5
B. 6/5
C. 7/5
D. 8/5
E. 9/5


Kudos for a correct solution.


\(\frac{w}{x} = \frac{2}{3}\) Or, \(\frac{w}{x} = \frac{8}{12}\)

And, \(\frac{w}{y} = \frac{8}{15}\)

So, \(w = 8\) , \(x = 12\) & \(y = 15\)

Thus, \frac{(x + y)}{y} = \frac{12 + 15}{15}

= \(\frac{27}{15}\)

= \(\frac{9}{5}\), answer will be (E)
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Re: If w/x = 2/3 and w/y = 8/15, then (x + y)/y = &nbs [#permalink] 14 Nov 2017, 08:34
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