average of x,y, & z

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average of x,y, & z

by jzebra10 » Sun Nov 20, 2011 8:40 am
If x+y=8z, then which of the following represents the average of x,y,and z, in terms of z.

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

And I don't understand the explanation given in the GMAT review book.

help!

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by Anurag@Gurome » Sun Nov 20, 2011 8:42 am
jzebra10 wrote:If x+y=8z, then which of the following represents the average of x,y,and z, in terms of z.
Given, (x + y) = 8z
Hence, (x + y + z) = (8z + z) = 9z

Now, average of x, y, and z = (x + y + z)/3 = (9z)/3 = 3z

The correct answer is B.
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by vishal chugh » Sun Nov 20, 2011 7:40 pm
take 3 numbers which satisfy the given equation
here x=4; y=4; z=1 (satisfies the given equation x+y = 8z;
so average becomes (4+4+1)/3= 3 or 3(1)= 3(z)