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How many terms of the GP 3, 3/2, 3/4, … sum to 3069/512?
A11
B8
C9
D10
Answer & Solution
Correct answer: D. 10
a = 3, r = 1/2. S_n = 3(1 − (1/2)ⁿ)/(1/2) = 6(1 − 1/2ⁿ) = 3069/512 ⇒ 1/2ⁿ = 1/1024 ⇒ n = 10.
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