A corroded metal plate was found in a submerged ocean vessel. The original dimensions of the plate were 25 x 10 x 5 cm. It is estimated that 7.6 kg of the plate had corroded away. Assuming the corrosion rate of this metal in saltwater is 150 mils/year and the its density is 4.5 g/cm3, determine how long ago the ocean vessel sank.