Nuclear energy derived from radioactive isotopes can be used to supply power to space vehicles. The output of the radioactive power supply for a certain satellite is given by the function y = 40e^-0.004t, where y is in watts and t is the time in days.
(a) How much power will be available at the end of 180 days?
(b) How long will it take for the amount of power to be half of its original strength?
(c) Will the power ever be completely gone? Explain.