The sum of three terms (numbers) of a G.P. is $3\dfrac{1}{2}$ and their product is 1; the numbers are :

1. $\dfrac{1}{2}, 1$ and 2

2. $\dfrac{1}{3}, 3$ and 9

3. $1, \dfrac{1}{2}$ and 2

4. $2, \dfrac{1}{2}$ and 1

The sum of 20 terms of the G.P. 10, 20, 40, …… is :

1. 10(2¹⁹ - 1)

2. 10(2²¹ - 1)

3. 10(2²⁰ - 1)

4. none of these

Find the sum of G.P. :

0.3 + 0.03 + 0.003 + 0.0003 + …… to 8 terms.

Find the sum of G.P. :

$1 - \dfrac{1}{2} + \dfrac{1}{4} - \dfrac{1}{8} + …….$ to 9 terms