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The average (arithmetic mean) of x, y, and 15 is 9.

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The average (arithmetic mean) of x, y, and 15 is 9. [#permalink]  27 Oct 2018, 16:48
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The average (arithmetic mean) of x, y, and 15 is 9.

 Quantity A Quantity B Average of x and y 6

A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.
[Reveal] Spoiler: OA

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Re: The average (arithmetic mean) of x, y, and 15 is 9. [#permalink]  28 Oct 2018, 15:44
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Expert's post
Carcass wrote:
The average (arithmetic mean) of x, y, and 15 is 9.

 Quantity A Quantity B Average of x and y 6

GIVEN: The average (arithmetic mean) of x, y, and 15 is 9.
We can write: (x + y + 15)/3 = 9
Multiply both sides by 3 to get: x + y + 15 = 27
Subtract 15 from both sides: x + y = 12

Average of x and y = (x + y)/2 = (12)/2 = 6

We get:
QUANTITY A: 6
QUANTITY B: 6

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Re: The average (arithmetic mean) of x, y, and 15 is 9. [#permalink]  29 Oct 2018, 08:17
Expert's post
Carcass wrote:
The average (arithmetic mean) of x, y, and 15 is 9.

 Quantity A Quantity B Average of x and y 6

A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.

Average of x, y and 15 is 9, so sum = x+y+15=9*3......x+y=12

A. average of x +y, so $$\frac{x+y}{2}=\frac{12}{2}=6$$
B. 6

so both are equal

C
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Some useful Theory.
1. Arithmetic and Geometric progressions : https://greprepclub.com/forum/progressions-arithmetic-geometric-and-harmonic-11574.html#p27048
2. Effect of Arithmetic Operations on fraction : https://greprepclub.com/forum/effects-of-arithmetic-operations-on-fractions-11573.html?sid=d570445335a783891cd4d48a17db9825
3. Remainders : https://greprepclub.com/forum/remainders-what-you-should-know-11524.html
4. Number properties : https://greprepclub.com/forum/number-property-all-you-require-11518.html
5. Absolute Modulus and Inequalities : https://greprepclub.com/forum/absolute-modulus-a-better-understanding-11281.html

Re: The average (arithmetic mean) of x, y, and 15 is 9.   [#permalink] 29 Oct 2018, 08:17
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