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# If x+y=8z, then which of the following represents the averag

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Manager
Joined: 04 Feb 2011
Posts: 59
Location: US
If x+y=8z, then which of the following represents the averag [#permalink]

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08 Feb 2011, 03:40
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If x+y=8z, then which of the following represents the average (arithmetic mean) of x, y, and z, in terms of z?

(A) 2z+1
(B) 3z
(C) 5z
(D) z/3
(E) 3z/2
Math Expert
Joined: 02 Sep 2009
Posts: 46991
If x+y=8z, then which of the following represents the averag [#permalink]

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08 Feb 2011, 04:01
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Lolaergasheva wrote:
If x+y=8z, then which of the following represents the average (arithmetic mean) of x, y, and z, in terms of z?

(A) 2z+1
(B) 3z
(C) 5z
(D) z/3
(E) 3z/2

The average of x, y and z equals to (x+y+z)/3 as x+y=8z then (x+y+)z/3=(8z+z)/3=9z/3=3z.

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Manager
Joined: 04 Jan 2013
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If x+y=8z then which of the following represents [#permalink]

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26 Jan 2013, 07:01
If x+y=8z then which of the following represents the arithmetric mean of x,y and z interms of z?

A.2z+1 B.3z C.5z D.z/3 E.3z/2
Manager
Joined: 12 Mar 2012
Posts: 88
Location: India
Concentration: Technology, Strategy
GMAT 1: 710 Q49 V36
GPA: 3.2
WE: Information Technology (Computer Software)
Re: If x+y=8z then which of the following represents [#permalink]

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26 Jan 2013, 07:22
3
Arithmetic mean of x, y and z = (x+y+z)/3
x+y = 8z so x+y+z = 8z + z = 9z.
Arithmetic mean = 9z/3 = 3z.

Please give a kudo if you like my explanation.
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Joined: 02 Sep 2009
Posts: 46991
Re: If x+y=8z then which of the following represents [#permalink]

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26 Jan 2013, 08:40
chiccufrazer1 wrote:
If x+y=8z then which of the following represents the arithmetric mean of x,y and z interms of z?

A.2z+1 B.3z C.5z D.z/3 E.3z/2

Merging similar topics. Refer to the solutions above.
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Joined: 21 May 2013
Posts: 28
Location: India
Concentration: Finance, Marketing
GMAT 1: 660 Q49 V32
Re: If x+y=8z, then which of the following represents the averag [#permalink]

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23 Aug 2013, 09:19
Lolaergasheva wrote:
If x+y=8z, then which of the following represents the average (arithmetic mean) of x, y, and z, in terms of z?

(A) 2z+1
(B) 3z
(C) 5z
(D) z/3
(E) 3z/2

Pick any number like X=12, Y=4 and Z= 2 so that X+Y=8Z, now then the arithmetic mean will be (12+4+2)/3=6. Now, just look at the answers and put the value of Z there.

(A) 2.2+1=5, but it should be 6.
(B) 3.2=6, it can be the answer, lets check us the other options
(C) 5.2=10, no
(D) 2/3, no
(E) (3.2)/2=3, no

so the answer will be B..
CEO
Joined: 12 Sep 2015
Posts: 2630
Re: If x+y=8z, then which of the following represents the averag [#permalink]

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11 Dec 2017, 12:10
1
Top Contributor
Lolaergasheva wrote:
If x+y=8z, then which of the following represents the average (arithmetic mean) of x, y, and z, in terms of z?

(A) 2z+1
(B) 3z
(C) 5z
(D) z/3
(E) 3z/2

Here's a solution that involves the INPUT-OUTPUT approach.

Given: x + y = 8z
So, one possible solution to this equation is x = 7, y = 9 and z = 2

Which of the following represents the average (arithmetic mean) of x, y, and z, in terms of z?
Average = (x + y + z)/2
= (7 + 9 + 2)/2
= 18/3
= 6

So, when we INPUT x = 2, the answer to the question is 6
So, we're looking for an answer choice that OUTPUTS a 6 when we INPUT x = 2

(A) 2(2) + 1 = 5. No good. We want 6. ELIMINATE
(B) 3(2) = 6. KEEP
(C) 5(2) = 10. No good. We want 6. ELIMINATE
(D) 2/3 = 2/3. No good. We want 6. ELIMINATE
(E) 3(2)/2 = 3. No good. We want 6. ELIMINATE

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Re: If x+y=8z, then which of the following represents the averag   [#permalink] 11 Dec 2017, 12:10
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