The rule of the <span>geometric sequence is 
a ⇒⇒⇒ </span><span>the first term
r ⇒⇒⇒ </span><span>common ratio
Given: the fourth term </span>(a4) <span>= 121.5 and the common ratio = 3 and n = 4
∴</span><span>
∴ a = 121.5/3³ = 121.5/27 = 4.5
So, T</span><span>he formula for this sequence will be</span><span>
</span>
a ⇒⇒⇒ </span><span>the first term
r ⇒⇒⇒ </span><span>common ratio
Given: the fourth term </span>(a4) <span>= 121.5 and the common ratio = 3 and n = 4
∴</span><span>
∴ a = 121.5/3³ = 121.5/27 = 4.5
So, T</span><span>he formula for this sequence will be</span><span>