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The average (arithmetic mean) of the 11 numbers in a list is [#permalink]
06 Mar 2018, 15:39

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The average (arithmetic mean) of the 11 numbers in a list is 14. If the average of 9 of the numbers in the list is 9, what is the average of the other 2 numbers?

Re: The average (arithmetic mean) of the 11 numbers in a list is [#permalink]
04 May 2018, 09:31

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Carcass wrote:

The average (arithmetic mean) of the 11 numbers in a list is 14. If the average of 9 of the numbers in the list is 9, what is the average of the other 2 numbers?

enter your value

Let's assign some variables: Let a, b, c, d, e, f, g, h, i, j, k be the ORIGINAL 11 numbers.

The average (arithmetic mean) of the 11 numbers in a list is 14. So, we can write: (a+b+c+d+e+f+g+h+i+j+k)/11 = 14 Multiply both sides by 11 to get: So, a+b+c+d+e+f+g+h+i+j+k = 154

If the average of 9 of the numbers in the list is 9 . . . So, we can write: (a+b+c+d+e+f+g+h+i)/9 = 9 Multiply both sides by 9 to get: So, a+b+c+d+e+f+g+h+i = 81

. . . what is the average of the other 2 numbers? We now have the following system: a+b+c+d+e+f+g+h+i+j+k = 154 a+b+c+d+e+f+g+h+i = 81

Subtract the bottom equation by the top equation to get: j + k = 73 So, the AVERAGE of j and k = (j + k)/2 = 73/2 = 36.5

Answer: 36.5

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Re: The average (arithmetic mean) of the 11 numbers in a list is
[#permalink]
04 May 2018, 09:31