GMAT prep DS question

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Source: — Data Sufficiency |

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Re: GMAT prep DS question

by parallel_chase » Sat Jul 19, 2008 2:12 pm
mlane25269 wrote:Hi! Can someone explain? Thanks!
The question asks us the following

[x+(x+1)+(x+2)+.....+(x+10)]/11=?

You can phrase the question as what is the value of x

Statement I

Average of first nine integers is 7

[x+(x+1)+(x+2)+.....+(x+8)]/9= 7

Sufficient.

Statement II

Average of last nine integers is 9

[(x+2)+(x+3).....+(x+10)]/9= 9

Sufficient.

Hence the answer is D.