- [Maximum mark: 7]
A geometric sequence has first term 80 and fourth term 0.74088.
(a) Find the second term. [3]
The first two terms of this geometric sequence are also the first term and eleventh term respectively, of an arithmetic sequence.
Let (S_n) denote the sum of the first (n) terms of the arithmetic sequence.
(b) Find the greatest value of (S_n), giving your answer to two decimal places. [4]