For a geometric progression, a(n) = a(1)*r^(n-1)
where a(n) is the nth term
r is the common ratio
n is the number of terms
First we need to obtain the common ratio by using a(2) and a(4). The number of terms (n) is 3.
Therefore
48 = 768* (r)^2
thus, r = 0.25
solving for a(7)
a(7) = 768 * (0.25)^(5)
a(7) = 0.75
