To solve this problem you must apply the proccedure shown below:
1. You have that a1=6 and r=1/3, therefore you must apply the following formula:
Sn=a(1-r^n)/1-r
2. When you substitute the values shown above, you obtain:
S5=6(1-(1/3)^5)/(1-(1/3))
S5=242/27
Therefore, the answer is 242/27