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What is the average (arithmetic mean) of x, y, and z?

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Joined: 24 Nov 2018
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What is the average (arithmetic mean) of x, y, and z?  [#permalink]

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New post 14 Jan 2019, 21:08
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Question Stats:

59% (01:18) correct 41% (01:37) wrong based on 75 sessions

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What is the average (arithmetic mean) of x, y, and z?

(1) —x − 4y + 3z = 14

(2) 5x + 8y + z = 26
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Joined: 02 Aug 2009
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Re: What is the average (arithmetic mean) of x, y, and z?  [#permalink]

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New post 14 Jan 2019, 21:27
1
divyadamahe wrote:
What is the average (arithmetic mean) of x, y, and z?

(1) —x − 4y + 3z = 14

(2) 5x + 8y + z = 26


We are looking for X+y+z..
Each statement gives us three variables,so each is not sufficient..

By looking at the two equations together we can see that the adding up will give us something in terms of what we are seeking..
So add the two statements..
5x+8y+z-x-4y+3z=26+14.....4x+4y+4z=40.....x+y+z=10..
Average is 10/3
Sufficient

C
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1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html
4) Base while finding % increase and % decrease : https://gmatclub.com/forum/percentage-increase-decrease-what-should-be-the-denominator-287528.html


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Re: What is the average (arithmetic mean) of x, y, and z?  [#permalink]

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New post 15 Jan 2019, 05:48
divyadamahe wrote:
What is the average (arithmetic mean) of x, y, and z?

(1) —x − 4y + 3z = 14

(2) 5x + 8y + z = 26


#1:
values of x,y,z not given
in sufficient
#2:
values of x,y,z not given
in sufficient

combining 1 & 2
we can determine x,y,z
sufficienet
IMO C
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Re: What is the average (arithmetic mean) of x, y, and z?  [#permalink]

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New post 01 Feb 2019, 22:08
divyadamahe wrote:
What is the average (arithmetic mean) of x, y, and z?

(1) —x − 4y + 3z = 14

(2) 5x + 8y + z = 26


To find: x+y+z / 3 -------(a)

from 1, When we substitute for x in (a), we cannot get a value for y and z

x = - (14+4y-3z)

-3y+4z/3

from 2, When we substitute for z in (a), we cannot get a value for x and y

26 - 4x -7y/3

But when we combine both the statements, we can get the value of

just add 1 and 2
4x + 4y + 4z = 40

x+y+z as 10

Average becomes 10/3

C
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Re: What is the average (arithmetic mean) of x, y, and z?   [#permalink] 01 Feb 2019, 22:08
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What is the average (arithmetic mean) of x, y, and z?

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