Question 761601
If 'a' is the first term, and 'r' the common ratio of the GP,

the sum to infinity is given by the formula {{{S = a/(1-r)}}}

Here since sum is given as 4 times first term, we can write the equation as:

{{{4*a = a/(1-r)}}}

Cancelling a from both sides,

{{{4 = 1/(1-r)}}}

i.e.

{{{1 - r = 1/4}}}

Solving

{{{r = 3/4}}}


:)