A differential manometer is used to measure the drop in pressure across a filter at a water (? = 1.00 g/cm3) processing plant. The density of the manometer fluid is 2.75 g/cm3. The height of the manometer fluid on side 1 is 324 mm. The height of the manometer fluid on side 2 is 326 mm. What is the pressure difference between points 1 and 2 in psi?