The sum of the first terms n in the infinite geometric sequence {1/4, 1/8, 1/16, ..} is \(15/32\). Find n.
+128407 r = 1/2
Sum of first n terms of an infinite series =
first term [ 1 - (r)^n ] / [ 1 - r ] =
(1/4) [ 1 - (1/2)^n ] / [ 1 -1/2 ] = 15/32
(1/4) [ 1 - (1/2)^n ] / (1/2) =15/32
(1/2) [ 1 - (1/2)^n ] = 15/32
1 - (1/2)^n = 30/32
1- (1/2)^n = 15/ 16
(1/2)^n = 1 -15/16
(1/2)^n = 1 /16
n = 4
