I need help with this please!!

Question

A radioactive substance decays 3% each day. If the initial amount of the substance was 400 grams, which of the following functions f models the remaining amount of the substance, in grams, t days later?

Answer 1

Hi! The formula for these types of problems is A = P (1-r)^t

A = end amount

P = initial amount

r = rate of decay (in decimal form)

t = time

In this case, P = 400 and r = 0.03. Our formula will be A = 400(1-.03)^t. This can be simplified to A = 400(.97)^t.

I hope that this helps!