Answer
$\sqrt[15] (y^{11})$
Work Step by Step
$\sqrt[3] y\times\sqrt[5] (y^{2})=y^{\frac{1}{3}}\times y^{\frac{2}{5}}$
We can further simplify by using the product rule, which holds that $a^{m}\times a^{n}=a^{m+n}$.
$y^{\frac{1}{3}}\times y^{\frac{2}{5}}=y^{(\frac{1}{3}+\frac{2}{5})}=y^{(\frac{5}{15}+\frac{6}{15})}=y^{\frac{11}{15}}=\sqrt[15] (y^{11})$