One for free:
Mass as a function of time: m(t)
Decay Rate of Element: dm/dt
A synthetic radioactive element decays at a rate proportional to its mass.
(a) write down a differential equation to represent this situation.
(b) If 30% of the element has decayed after 24 hours, what percentage is left after 48 hours?
c) How long does it take for 90% of the element to decay?