Hippos spend much of their lives in water, but amazingly, they don't swim. They have, like manatees, very little body fat. The density of a hippo's body is approximately 1030 kg/m3kg/m3, so it sinks to the bottom of the freshwater lakes and rivers it frequents--and then it simply walks on the bottom. A 1500 kg hippo is completely submerged, standing on the bottom of a lake. What is the approximate value of the upward normal force on the hippo?

I have the right concept of mg=F buoyancy + F normal, but I'm confused about which density should I use for the F buoyancy calculation.