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# If the average (arithmetic mean) of x, y and 15 is 9, and the average

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Math Expert
Joined: 02 Sep 2009
Posts: 58335
If the average (arithmetic mean) of x, y and 15 is 9, and the average  [#permalink]

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18 Oct 2018, 02:19
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Difficulty:

15% (low)

Question Stats:

94% (01:21) correct 6% (00:58) wrong based on 47 sessions

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If the average (arithmetic mean) of x, y and 15 is 9, and the average of x, 2y and 2 is 7, then y =

A. 5
B. 6
C. 7
D. 8
E. 9

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Joined: 08 Oct 2018
Posts: 3
Re: If the average (arithmetic mean) of x, y and 15 is 9, and the average  [#permalink]

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18 Oct 2018, 05:59
(x+y+15)/3=9
=>x+y=12...1
again,(x+2y+2)/3=7
=>x+2y=19....2
2-1,we can get y=7
Ans option C

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Joined: 07 Jul 2012
Posts: 369
Location: India
Concentration: Finance, Accounting
GPA: 3.5
Re: If the average (arithmetic mean) of x, y and 15 is 9, and the average  [#permalink]

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18 Oct 2018, 09:10
$$\frac{x+y+15}{3}$$= 9

x+y+15=27
x+y= 12..........(1)

$$\frac{x+2y+2}{3}$$= 7

x+2y+2= 21
x+2y= 19.........(2)

Solving (1) and (2)
y= 7

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Re: If the average (arithmetic mean) of x, y and 15 is 9, and the average   [#permalink] 18 Oct 2018, 09:10
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