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    Question

    Find the sum of 12th terms of a geometric progression

    whose 1st term is 8 and common ratio is 2.
    A 3280 Correct Answer Incorrect Answer
    B 3060 Correct Answer Incorrect Answer
    C 3120 Correct Answer Incorrect Answer
    D 3320 Correct Answer Incorrect Answer

    Solution

    GP = Sn=a(rn – 1)/(r – 1) Where a = 12, r = 2 Sum of 12 terms = a(r8 – 1)/(r – 1) ⇒ 12 × [(28 – 1)/(2 – 1)] ⇒ 12 × [256 – 1] ⇒ 12 × 255 ⇒ 3060

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