Answer: A) 1/2
Step-by-step explanation:
In a geometric sequence, the consecutive terms differ by a common ratio. The formula for determining the nth term of a geometric progression is expressed as
Tn = ar^(n - 1)
Where
a represents the first term of the sequence.
r represents the common ratio.
n represents the number of terms.
If the third term is 20, it means that
T3 = 20 = ar^(3 - 1)
20 = ar²- - - - - - - - - - 1
If the third term is 20, it means that
T5 = 5 = ar^(5 - 1)
5 = ar⁴- - - - - - - - - - 2
Dividing equation 2 by equation 1, it becomes
5/20 = r⁴/r²
1/4 = r^(4 - 2)
(1/2)² = r²
r = 1/2
