A rectangular water tank is composed of three layers of polycarbonate, each 1 mm thick. The middle layer contains 0.1 mg/cm3 of bisphenol-A (BPA) as a plasticizing agent to keep the container walls slightly flexible. The diffusion coefficient of BPA in polycarbonate is 1.5 x 10-10 cm2 /s. Make a graph of the polycarbonate concentration in the inside layer (i.e., the layer contacting the water) one month after the tank in constructed. Is your solution valid for a time of 90 days? The solution for an extended source of finite extent is given by: = 0.5 ! ' + "#$ &'(, + + ")$ &'(,.