The radioactive element polonium decays a Q(t) = Q0 · 2−(t/140) If the amount of polonium left after 280 days is 90 mg, what was the initial amount present?

Question

Radioactive Decay

 The radioactive element polonium decays according to the law given below where Q₀

 is the initial amount and the time t is measured in days.

Q(t) = Q₀ · 2^−(t/140)

If the amount of polonium left after 280 days is 90 mg, what was the initial amount present?

Answer 1

Q(280) = Q₀2^-(280/140)=90

Q₀(2)^-2=90

Q₀(1/2)²=90

Q₀(1/4)=90

Q₀=360

Here is a Desmos graph you can use for confirmation.

desmos.com/calculator/btyzrgtedv