A U tube with both ends open to the atmosphere, is partially filled with water. Oil, which is immiscible with water, is poured into one side until it stands at a distance of 10 mm above the water level on the other side. Meanwhile, the water rises by 65 mm from its original level (see diagram). The density of the oil is           [2017]

[IMAGE 92]
 

Two non-mixing liquids of densities $\rho$ and $n\rho$ $(n>1)$ are put in a container. The height of each liquid is $h$. A solid cylinder of length $L$ and density $d$ is put in this container. The cylinder floats with its axis vertical and length $pL$ $(p<1)$ in the denser liquid. The density $d$ is equal to           [2016]