The halflife of plutonium234 is 9 hours If 70 milligrams is

The half-life of plutonium-234 is 9 hours. If 70 milligrams is present now, how much will be present in 6 days? (Round your answer to three decimal places.)

Solution

k ( decay constant) = 0.693/half life = 0.693/9 = 0.077/ hr

Radioactive decay equation: A (t) = Aoe^(-kt)

Ao ( intial qty.) = 70 milligms

how much will be present in 6 days? = 6*24 = 144hrs

A = 70 e^(-0.077*144) = 70*0.000015 =0.00105 milligms = 0.001 milligms