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Posted by on Monday, July 4, 2011 at 5:01am.

What is the sum to 15 terms of an arithmetic progression whose 8th term is 4?

  • arithmetic - , Tuesday, February 14, 2017 at 7:26pm

    W.k.t,
    Sn = n/2 {2a + (n-1)d} then
    S15 = 15/2 {2a + 14d}
    =15/2 {2(a+7d)}
    wkt, a+7d = 15
    S15 = 15(15)=225

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