Question

What is the sum of the infinite series \( S = \sum_{n=0}^{\infty} \frac{1}{3^n} \)?

• A. \( \frac{3}{2} \)
• B. \( \frac{1}{2} \)
• C. 2
• D. 3

Hint:

For an infinite geometric series with \( |r|<1 \), the sum is given by \( S = \frac{a}{1 - r} \).

Answer 1

The Correct Option is B

The series is a geometric progression where the initial value is \( a = 1 \) and the constant multiplier is \( r = \frac{1}{3} \).

The total of an unending geometric progression is determined by the formula: \[ S = \frac{a}{1 - r}. \] 

With \( a = 1 \) and \( r = \frac{1}{3} \) inserted: \[ S = \frac{1}{1 - \frac{1}{3}} = \frac{1}{\frac{2}{3}} = \frac{3}{2}. \] 

Therefore, the sum of the progression is \( \frac{3}{2} \).