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Answers
The arithmetic progression sequence has 15 terms in it. The 8th term is the middle term. So we can take A as the 8th term and keep on adding the common difference D to the successive previous terms to the right of A till we reach A + 7D. Similarly we can keep subtracting D from successive previous term to the left of A till we reach A - 7 D.
The 15 terms of the arithmetic sequence so obtained would be;
A - 7D, A - 6 D, A - 5 D, A - 4 D, A - 3 D, A -2 D, A - D, A, A+D, A+2 D, A +3 D, A+ 4 D, A +5 D, A+ 6D, and A +7 D.
Sum of the 15 terms of this arithmetic sequence = (A - 7 D) + (A - 6 D) + (A - 5 D) + (A - 4 D) + (A - 3D) + (A - 2 D) + (A - D) + (A) + (A +D) + (A + 2 D) + (A +3 D) + (A +4 D) +(A +5 D) +(A + 6 D) + ( A +7 D) = 15 A = 480 (given)
Therefore,
A = 480/15 = 32