Question

What sequence is geometric and has 1/4 as it's fifth term and 1/2 as the common ratio?

Answer 1

Use
a(i)=a1*r^(i-1)
we know that a(5)=a1*(1/2)^(5-1)=a1/16 = 1/4
solve for a1=(1/4)*16=4
=>
sequence: 
4,2,1,1/2,1/4,1/8,1/16,...