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Asked by buttercup | 9th Mar, 2012, 08:02: PM

Expert Answer:

In this question it can be seen that a1 = 15 , a2 < 13.5 , a3 < 12 ..........
Now since sum of the squares of first eleven terms is 990 , this means that there are some neagtive nos as well
So , we get
a1 = 15 , a2 = 12 , a3 = 9 , a4 = 6 , .......... , a10 = -12 , a11 = -15
Now sum of all the terms is 0 , So their average is 0

Answered by  | 11th Mar, 2012, 03:12: PM

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