Answer:
3/4
Step-by-step explanation:
We know a geometric sequence has the formula: a_n = a_1 * r^(n-1)
a_2 = 20
a_4 = (45/4)
so... a_2 = a_1* r^(2-1) = 20
and a_4 = a_1* r^(4-1) = (45/4)
a_1 * r = 20
a_1* r^3 = (45/4)
a_1 = 20/r
(20/r) * r^3 = (45/4)
20 * r*r = 45/4
r*r = 45/80 = 9/16
r = 3/4 or r = -3/4 it must be positive.
common ratio is r = 3/4
