Find the density of seawater at a depth where the pressure is $420$atm if the density at the surface is $1050k\frac{g}{m^3}.$ Seawater has a bulk modulus of $2\mathrm{.}3{10}^9\frac{N}{m^2}.$ Bulk modulus is defined to be

$B-=\frac{{}_{0}P}{}$

Answer in units of $k\frac{g}{m^3}.$