Find the sum to infinity of the geometric series 10 + 20/3 + 40/9 + ...
Answer and explanation
Correct answer: B. 30
- Step 1: The ratio is r = 2/3, and |r| < 1, so the series converges.
- Step 2: S = a/(1 - r) = 10/(1 - 2/3) = 30.
Answer
30.
Why not the others: '15' divides by r instead of 1 - r; '16.67' adds the first two terms only; '20' starts the sum at the second term.
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