Question

What is the value of the fourth term in a geometric sequence for which a1=10 and r=0.5

Answer 1

a2 = r a1
a3 = r a2 = r^2 a1
a4 = r a3 = r^3 a1

plug in a1 and r for answer

Answer 2

Use the general term of G.P.
an=ar^n-1

Answer 3

APEX 1.25