A U tube with both ends open to the atmosphere, is partially filled rvith u,ater. Oil, which is imeriscible with water, is poured into one side until itstands at a distance of 10 mtrr 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 :

Question

$\begin{array}{1 1} (1) 650\;kg\;m^{-3}\\ (2) 425\;kg\;m^{-3} \\ (3) 800\;kg\;m^{-3} \\ (4)928 \;kg\;m^{-3} \end{array} $