The density of a liquid is to be determined by an old 1-cm-diameter cylindrical hydrometer...

The density of a liquid is to be determined by an old 1-cm-diameter cylindrical hydrometer whose division marks are completely wiped out. The hydrometer is first dropped in water, and the water level is marked. The hydrometer is then dropped into the other liquid, and it is observed that the mark for water has risen 0.5 cm above the liquid-air interface. If the height of the water mark is 10 cm, determine the density of the liquid.