Phosphorus-32 (P-32) has a half-life of 14.2 days. If 200 g of this substance are present initially, find the amount Q(t) present after t days. (Round your growth constant to four decimal places.)

Question

How fast is the P-32 decaying when t = 21.5? (Round your answer to three decimal places.)

Answer 1

Q(t) = 200 (1/2)^(t/14.2)
or
Q(t) = 200(.5)^(.0704t)

Q '(t) = (200/14.2) (.5)^(t/14.2)

so when t = 21.5
Q ' (t) = (200/14.2) (.5)^(21.5/14.2)
= 4.931 g/day