The equation for a finite geometric sequence is Sn=a1((1-r^n)/(1-r))
a1=1
r=.5/1=.5
n=5
Using the equation:
Sn=a1((1-r^n)/(1-r))=1((1-.5^5)/(1-.5))=1((1-.03125)/(1-.5))=1(.96875/.5)=1*1.9375=1.9375
Answer Choices:
A. 1/12 or .083
B. 93
C. -1/48 or -.02083
D. 31/16 or 1.9375
The Answer is D. 31/16