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What is the sum to infinity of the given geometric progression?2, 0.2, 0.02, 0.002, ......
Question

What is the sum to infinity of the given geometric progression?

2, 0.2, 0.02, 0.002, ......

A.

2.22222...

B.

3.00

C.

99200\frac{99}{200}​​

D.

20099\frac{200}{99}​​

Correct option is A

Identify the First Term (a) and Common Ratio (r) First term (a): 2 Common ratio (r):r=0.22=0.1(or)0.020.2=0.1(consistent)Check for ConvergenceFor an infinite GP to converge (have a finite sum), the absolute value of the common ratio must satisfy:r<1Here, r=0.1 meets this condition.Apply the Sum to Infinity FormulaThe sum S of an infinite GP is given by:S=a1rSubstitute a=2 and r=0.1:S=210.1=20.9=209\begin{aligned}&\textbf{Identify the First Term } (a) \text{ and Common Ratio } (r) \\[6pt]&\bullet\ \text{First term } (a):\ 2 \\[4pt]&\bullet\ \text{Common ratio } (r): \\&r = \frac{0.2}{2} = 0.1 \quad \text{(or)} \quad \frac{0.02}{0.2} = 0.1 \quad \text{(consistent)} \\[12pt]&\textbf{Check for Convergence} \\[4pt]&\text{For an infinite GP to converge (have a finite sum), the absolute value of the common ratio must satisfy:} \\&\qquad |r| < 1 \\[4pt]&\text{Here, } r = 0.1 \text{ meets this condition.} \\[12pt]&\textbf{Apply the Sum to Infinity Formula} \\[4pt]&\text{The sum } S_\infty \text{ of an infinite GP is given by:} \\&S_\infty = \frac{a}{1 - r} \\[6pt]&\text{Substitute } a = 2 \text{ and } r = 0.1: \\&S_\infty = \frac{2}{1 - 0.1} = \frac{2}{0.9} = \frac{20}{9}\end{aligned}​​

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