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# 21, 17, 9, 12, x, 5, 0, y What is the value of x in the list above?

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Joined: 02 Sep 2009
Posts: 58320
21, 17, 9, 12, x, 5, 0, y What is the value of x in the list above?  [#permalink]

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31 Jan 2019, 01:28
00:00

Difficulty:

5% (low)

Question Stats:

93% (00:55) correct 7% (01:33) wrong based on 31 sessions

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21, 17, 9, 12, x, 5, 0, y

What is the value of x in the list above?

(1) y = x − 4

(2) The arithmetic mean of the numbers in the list is 10.

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Re: 21, 17, 9, 12, x, 5, 0, y What is the value of x in the list above?  [#permalink]

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31 Jan 2019, 01:53
Bunuel wrote:
21, 17, 9, 12, x, 5, 0, y

What is the value of x in the list above?

(1) y = x − 4

(2) The arithmetic mean of the numbers in the list is 10.

we are asked to find out the value of x.

Statement 1: y = x -4.

21 + 17 + 9 +12 + x +5 + 0 +y

21 + 17 + 9 + 12 + x + 5 + 0 + x - 4

Still it's impossible to find out the value of x as we don't know the total.

Statement 2; average is given. Not sufficient. we have 2 variables in the stem .

Combining : Sufficient. Statement 1 helps us reduce the number of variables and statement 2 gives us total.

21 + 17 + 9 + 12 + x + 5 + 0 + x - 4 = 10*8

2x + 60 = 80

2x = 20

x = 10.

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Re: 21, 17, 9, 12, x, 5, 0, y What is the value of x in the list above?  [#permalink]

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31 Jan 2019, 03:26
Bunuel wrote:
21, 17, 9, 12, x, 5, 0, y

What is the value of x in the list above?

(1) y = x − 4

(2) The arithmetic mean of the numbers in the list is 10.

#1
value of x & y not know in sufficient
#2
mean = 10
so x+y = 10 * 8 - 64
x+y=16
not sufficient
1& 2
combine
2x=20
x= 10
sufficient
IMO C
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Re: 21, 17, 9, 12, x, 5, 0, y What is the value of x in the list above?   [#permalink] 31 Jan 2019, 03:26
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