Question

find the sum of all 11 terms of A.P. whose midle term is 30
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Answer 1

Answer:

Sum of all 11 terms = 330

Explanation:

The AP has 11 terms. Hence, the middle term is the sixth term.

Given: Sixth term = 30

Let "d" be the common difference of the AP.

Hence the 11 terms of the AP may be written as:

30 - 5d, 30 - 4d, 30 - 3d, 30 - 2d, 30 - d, 30, 30 + d, 30 + 2d, 30 + 3d, 30 + 4d and 30 + 5d

Sum of these 11 terms = 30 + 30 + ...11 times

                                     = 30*11

                                     = 330