Certain radioactive material decays in such a way that the mass remaining after t years is given by the function: m(t) = 500e-0.05t where m(t) is measured in grams. (Round answers to 1 decimal place) (a) Find the mass at time t = 0. Your answer is grams. (b) How much of the mass remains after 15 years? Your answer is grams. (c) How long will it take for the sample to lose half of its mass? Your answer is years