Price of a Commodity The unit price of a certain commodity is given by the following where p is measured in dollars and t is measured in months. p = f(t)=7+4e-4t (a) Determine whether f(t) is increasing or decreasing over (0, 0). O increasing O decreasing (b) Determine whether f(t) is concave up or down on (0, 0). O upward O downward (c) Evaluate the limit as t→ ∞ of f(t). (Note: This value is called the equilibrium price of the commodity, and in this case, we have price stability.)