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The sum to infinity of a geometric progression is 100. Find its first term if th...

Question

The sum to infinity of a geometric progression is 100. Find its first term if the common ratio is $$\frac{1}{4}$$

A) 75

B) 70

C) 65

D) 60

Explanation:

S = $$\frac{a}{1-r}$$
R $$\lt$$ 1
$$\therefore$$ 100 = $$\cfrac{a}{(1-\frac{1}{4})}$$
100 $$\times \frac{3}{4} = a$$
A = 75

Explanation provided by Holarmilekan Amin

Dicussion (1)

• S = $$\frac{a}{1-r}$$
R $$\lt$$ 1
$$\therefore$$ 100 = $$\cfrac{a}{(1-\frac{1}{4})}$$
100 $$\times \frac{3}{4} = a$$
A = 75