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by dtweah » Wed May 13, 2009 10:19 am
The first three terms of a sequence are 1,7,8. If the average of the first four terms is 7 then the sum of the digits of the fourth term is
(a) 3
(b) 4
(c) 6
(d) 8
(e) 9
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by VP_Jim » Wed May 13, 2009 11:00 am
If the average of the first four terms is 7, and we know the first three digits, we can set up an equation:

(1+7+8+x)/4 = 7

Where x=the fourth value. Solving for x, we find that x=12.

So, the sum of its digits are 1+2=3.
Jim S. | GMAT Instructor | Veritas Prep
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