Answer
15 m/s
Work Step by Step
Please see the attached image first.
Here we use the Bernoulli's equation, $P+\frac{1}{2}\rho V^{2}+\rho gy = constant$
Where $P- Pressure$, $\frac{1}{2}\rho V^{2}-Kinetic\space energy\space per\space unit \space volume$, $\rho gy- Gravitational \space potential \space energy \space per\space unit \space volume.$
Let's plug known values into this equation.
$P_{1}+0+\rho gh=P_{2}+\frac{1}{2}\rho V_{hole}^{2}+0$
$\frac{2(P_{1}-P_{2})+2\rho gh}{\rho}=V_{hole}^{2}$ ; Let's plug known values into this equation.
$\frac{2(186\times10^{3}-10^{5})N/m^{2}+2\times10^{3}kg/m^{3}\times9.8\space m/s\times2.68\space m}{1000\space kg/m^{3}}=V_{hole}^{2}$
$V_{hole}=15 m/s$
