Here's the question: Water and then oil are poured into a U-shaped tube, open at both ends, and do not mix. They come to equilibrium as shown in the figure below, where y oil = 26.9 cm and y water=18.6 cm. What is the density of the oil? (Take the density of water as 1000 kg/m3.) I know that I need to use the P= Po+pgh somewhere and that where the two liquids are at equal height the pressure below that is equal... but I can't seem to get the right answer. I know it is simple- so can anyone help?