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

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If x + y= 8z, then which of the following represents the ave  [#permalink]

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New post 19 Feb 2014, 01:21
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The Official Guide For GMAT® Quantitative Review, 2ND Edition

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

Problem Solving
Question: 104
Category: Arithmetic Percents
Page: 75
Difficulty: 550


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Re: If x + y= 8z, then which of the following represents the ave  [#permalink]

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New post 19 Feb 2014, 01:21
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SOLUTION

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.

Answer: B.
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Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


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Re: If x + y= 8z, then which of the following represents the ave  [#permalink]

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New post 19 Feb 2014, 02:48
Option B.
Average of x,y and z=>(x+y+z)/3
x+y=8z(given)
Replacing we get,9z/3=3z
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Re: If x + y= 8z, then which of the following represents the ave  [#permalink]

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New post 24 Feb 2014, 05:06
Bunuel wrote:
The Official Guide For GMAT® Quantitative Review, 2ND Edition

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

Problem Solving
Question: 104
Category: Arithmetic Percents
Page: 75
Difficulty: 550


GMAT Club is introducing a new project: The Official Guide For GMAT® Quantitative Review, 2ND Edition - Quantitative Questions Project

Each week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution.

We'll be glad if you participate in development of this project:
1. Please provide your solutions to the questions;
2. Please vote for the best solutions by pressing Kudos button;
3. Please vote for the questions themselves by pressing Kudos button;
4. Please share your views on difficulty level of the questions, so that we have most precise evaluation.

Thank you!



Average of x,y,z is (x+y+z)/3=(8z+z)/3=3z
:)
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Re: If x + y= 8z, then which of the following represents the ave  [#permalink]

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New post 12 Jan 2017, 15:29
Bunuel 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



AM of x, y, z = (x+y+z)/3 = (8z+z)/3 = 3z

Correct Option: B
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Re: If x + y= 8z, then which of the following represents the ave  [#permalink]

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New post 13 Jan 2017, 04:47
x+y=8z then (x+y+)z/3=(8z+z)/3=9z/3=3z.
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Re: If x + y= 8z, then which of the following represents the ave  [#permalink]

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New post 16 Jan 2017, 18:03
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Bunuel 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


We need to determine the average of x, y, and z. In other words:

(x + y + z)/3 = ?

Since x + y = 8z, we can substitute 8z for x + y in our average formula and we have:

(8z + z)/3 = 9z/3 = 3z

Answer: B
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Re: If x+y=8z, then which of the following represents the averag  [#permalink]

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New post 11 Dec 2017, 12:10
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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


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
Let's check the answer choices...

(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

Answer: B

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Re: If x + y= 8z, then which of the following represents the ave  [#permalink]

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Re: If x + y= 8z, then which of the following represents the ave &nbs [#permalink] 12 Feb 2018, 05:51
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