Answer
let Vt be the total volume of ice berg
V_f be the volume displaced by the ice berg
fraction of visible ice berg
visible fraction = [tex]\dfrac{V_T-V_F}{V_T}[/tex]
= [tex]1 - \dfrac{V_F}{V_T}[/tex]
we know mass of iceberg is equal to the mass of fluid displaced
[tex]\rho_T V_T = \rho_f V_f[/tex]
[tex] \dfrac{V_F}{V_T} = \dfrac{\rho_T}{\rho_F}[/tex]
now,
= [tex]1 -\dfrac{\rho_T}{\rho_F}[/tex]
a) when ice berg float in the salt water
visible fraction = [tex]1 -\dfrac{\rho_T}{\rho_F}[/tex]
visible fraction = [tex]1 -\dfrac{917}{1024}[/tex]
visible fraction = 0.10 = 10%
b) when ice berg float in the freshwater
visible fraction = [tex]1 -\dfrac{\rho_T}{\rho_F}[/tex]
visible fraction = [tex]1 -\dfrac{917}{998}[/tex]
visible fraction = 0.081 = 8.1%