The EFISCEN wood product model classifics wood products according to their life - span. There arc four classifications: short (1 year), medium short (4 years), medium long (16 years), and long (50 years). Based on data obtained from the European Forest Institute, the percentage of remaining wood products are f years for wood products with long life - spans (such as those used in the building industry) is given by P(t ) = 100.3952 1+0.03160.0581 (a) What is the decay rate? (b) What is the percentage of remaining wood products after 10 years? (c) How long does it take for the percentage of remaining wood products to reach 50%? (d) Explain why the numerator given in the model is reasonable