25 g of polonium-210 is decaying exponentially. After 50 days 19.5 g of polonium-210 is left.
(a) Write a function in the form y = y₀e^kt giving the number of grams of polonium-210 after t days.
(b) Write the function from part (a) in the form y = y₀a^t/50.
(c) Use your answer from part (a) to find the half-life of polonium- 210.