Riemann sum help!!!!

blahblah33

1. The problem statement, all variables and given/known data
Use Riemann sum with c_i= i³/n³
f(x)= [tex]\sqrt[3]{x}[/tex] +12
from x=0 to x=18
n= 6 subintervals
Approximate the sum using Riemann's Sum

2. Relevant equations
[tex]\Sigma f(ci) \Delta[/tex] xi
is the equation for riemanns sum i think

3. The attempt at a solution
i tried plugging in stuff using that, but i must've done something wrong because the answer i got was 200 off the actual area under the curve...

blahblah33

also, is my original equation for riemann's sum correct? is there a limit involved?