At the bottom of the ocean at 10.92 km the pressure is 1.16*10^8 pa. If the pressure is calculated ignoring the change of density the pressure is 1.10*10^8 pa I have to calculate the water density at the bottom using the compressibility and the actual pressure. Since k= - Delta V/Vo*DeltaP DeltaP*k= - DeltaV/Vo and V=m/rho DeltaP*k=-(rho1-rho2)/rho2 where rho1 and rho2 are the water density at the surface and at the bottom respectively. I end up with: rho2=-rho1/(DeltaP*k -1) From this I get rho2 as 1033 pa but I should get 1080 pa Could someone please give me a hint to what I am doing wrong? Thanks.