You may have used the correct formula for the volume of a cone, $\displaystyle{V}=\frac{{1}}{{3}}\pi{{r}}^{{2}}{h}\usepackage{cmbright}\Huge\$ , but switched the values for the radius and the height. In this problem, $\displaystyle{r}={10}\usepackage{cmbright}\Huge\$ and $\displaystyle{h}={5}\usepackage{cmbright}\Huge\$ .