Answer: (C) = 765/128
Explanation:
Formula for finding the sum of a geometric series is in two form namely
i) Sn = a(1 - r[^{n})
------------- when r ∠ 1
1 - r
ii) Sn = a( r ^{n} - 1 )
--------------- when r greater than 1
r - 1
From the question, a = 3, n = 8 and r = 1/2 or o.5
from the formula i and ii above
i will be applicable because r ∠ 1
S8 = 3( 1 - 1/2^{8])
----------------
1 - 1/2
= 3 ( 1 - 1/256)
-----------------
1/2
= 3( 256 -1 /256)
-------------
1/2
= 3(255/256)
----------------
1/2
= 3 x 255 x 2
----------------
256
= 765/128