Find the sum of the infinite geometric series: 12 + 4 + 4/3 + 4/9 + ...
Answer and explanation
Correct answer: A. 18
- Step 1: Identify first term a = 12 and common ratio r = 4 / 12 = 1/3.
- Step 2: Since |r| = 1/3 < 1, the series converges to S = a / (1 - r).
- Step 3: Calculate: S = 12 / (1 - 1/3) = 12 / (2/3) = 12 * (3/2) = 18.
Answer
18.
Why not the others: Option 16 uses r = 1/4 (12 / 0.75). Option 24 calculates 12 / (1/2). Option 15 miscalculates 12 * 1.33.
Practise more Quantitative Reasoning and Algebra.
Free questions with an explanation for every one, and full timed University of Bahrain Aptitude Test (UOB Aptitude) mock tests.
More Quantitative Reasoning and Algebra questions
- Solve for x in the linear equation: 3(2x - 5) - 4(x + 2) = 7.
- If a store increases the price of an electronic device by 20% and later discounts the new price by 25%, what is the overall percentage chang…
- Find the solution set for the absolute value inequality: |2x - 7| <= 9.
- Solve the quadratic equation for real roots: 2x^2 - 5x - 12 = 0.
- If 5 workers can build a wall in 12 days, how many days will 6 workers take to build the identical wall working at the same pace?
- Simplify the algebraic rational expression: (x^2 - 16) / (x^2 + 7x + 12).