Question

If -1 < r < 1, then the sum of infinite number of a geometric series is
1. \(\frac{{a\left( {{r^n} - 1} \right)}}{{r - 1}}\)
2. \(\frac{{a\left( {1 - \;{r^n}} \right)}}{{1 - r}}\)
3. \(\frac{a}{{1 - r}}\)
4. \(na\)

Answer 1

Correct Answer - Option 3 : \(\frac{a}{{1 - r}}\)

Calculations :

If the first term in a geometric series is a and common ratio is less than 1, then,

Sum of infinite series = a/(1 - r) 

∴ The correct choice is option 3.