EXAMPLE 1: M = 400(1.05) / The equation above models the mass M, in nanograms, of a particle after t years. Based on the ec which of the following best describes the mass of the particle over time? A) It increases by 5% every 4 months. B) It increases by 5% every 3 years. It increases by 5 nanograms every 4 months. D) It increases by 5 nanograms every 3 years. We have an exponential aquati