A body is floating in oil of density 0.8 $gm/c{m}^3$ with 50% of its volume submerged in the oil. What percent of its volume will remain above the water srface when the body floats in water?

If $\sigma gm/c{m}^3$ be the density of the material of the body, then when it is floating in oil

$V\times \sigma \times g=\frac{V}{2}\times 0.8\times g\Rightarrow \sigma =0.4gm/c{m}^3$

when floating in water let V' be the submerged volume.

$\begin{array}{l}\therefore V^1\times 1\times g=V\times 0.4\times g\Rightarrow V^1=0.4\\ \therefore \frac{V-V^1}{V}=1-\frac{V^1}{V}=1-0.4=0.6=60\%\end{array}$