1. The problem statement, all variables and given/known data To verify her suspicion that a rock specimen is hollow, a geologist weighs the specimen in air and in water. She finds that the specimen weighs twice as much in air as it does in water. The density of the solid part of the specimen is 5.0 x 10^3 kg/m3. What fraction of the specimen’s apparent volume is solid? 2. Relevant equations Buoyant force = weight of water displaced Weight = density * volume * g 3. The attempt at a solution I don't even know... Pr=density rock Pa=density air Pw=density water Vs=volume solid Vh=volume hollow I thought that maybe: Weight of rock in air = Pr*vs*g+Pa*vh*g Therefore, weight of rock in water = (Pr*vs*g+Pa*vh*g)/2 And that's as far as I got. And I don't even think that's right. I'm so lost.