The sum of the first five terms of a Geometric Sequence is 155 and the fifth term is 80. What is the 6th term?
5, 10, 20, 40, 80, 160, 320, 640......and so on.
1st term=5, common ratio=2
a1- first term. an=qn-1*a1. Sum of first 5 terms- a1*(q5-1)/(q-1)=155
fifth term=80=a5=a1*q4----->a1=80/q4
+14 
