Answer:
-0.329
Step-by-step explanation:
The formula for Geometric ratio is
an = ar^n - 1
Where
a = First term = 18
r = Common ratio = ?
n = Number of term= 6
Hence
a6 = 18 × r^6-1
From the question
a6 = -2/29
Hence:
-2/29 = 18 × r^6-1
-2/29 = 18 × r⁵
Divide both sides by 18
-2/29 ÷ 18 = 18 × r⁵/18
-2/29 × 1/18 = r⁵
r⁵ = -1/261
Take the fifth root of both sides
⁵√(r⁵) = ⁵√(-1/261)
r = -0.3286032834
Approximately = -0.329
Therefore, Common ratio = -0.329
